Amid all the excitement and speculation surrounding bitcoin's price over the last couple of months, it's important to remember: to be worth anything at all, bitcoin must be accepted by merchants and used by regular customers on a day-to-day basis.

Several online businesses accept bitcoin as a fast and simple, fee-free way to transact, but there have been a few more hurdles in introducing the currency to physical traders.

There are payment processor accounts to set up, landlords and suppliers who accept only fiat currencies, and the odd pieces of clunky point-of-sale software and hardware.

Sometimes, even the promise of no credit card or bank processing fees isn't enough to convince busy store owners to try a radical payment system still in its early experimental phase.

So, we are bringing you the real-world bitcoin pioneers: the store owners and charities who believed enough to try bitcoin out, the evangelists who went to extreme lengths and places to promote its usefulness, and the publicity stunts that caught the attention of the general public.

Thanks to their actions, at the end of 2013 'bitcoin' is now a familiar word in the cultural mainstream, even among those who know little of its merits.

This story trickled into prominence back in early November. There was no official announcement from the parent company and no indication that they ever approved of it, but people in various places around the world noticed some Subway sandwich outlets had started to accept bitcoin.

If true, it would be one of the first examples of a major brand to do so, even if only at a few independent franchises. It started in Moscow in August with an Instagram snap of a Subway outlet offering a 10% discount for people paying in bitcoin.

It was followed by a tweet (supposedly of the same store) in early November and in subsequent weeks by Subways in Bratislava, Slovakia and Allentown, Pennsylvania also joining the bitcoin party. There are also reports another subway in Brno, Czech Republic is now accepting bitcoin as well.

So far it seems to be just these four stores, but Subway's popularity and the attention they've received has led to a grassroots campaign by fans lobbying their own local stores to jump on board.

Bitcoins, Richard Branson and ... space travel! There, you have everything you need to grab the headlines for a couple of days. In late November, Richard Branson became one of the highest-profile business owners to accept bitcoin through his company Virgin Galactic.

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Virgin Galactic promises to offer the first flights to suborbital space available to the general public, starting in 2014.

You can now spend your bitcoins on a rocket flight to space, and Branson said one passenger had already done so.

"Bitcoins aren’t yet formally recognized by governments as a currency but with some regulation I hope that it will become more widely accepted."

"A few years ago many people had doubts about whether Virgin Galactic would ever get off the ground. Now we have gone supersonic, are a long way along the testing process, and are looking forward to launching commercial space travel," he wrote in a post on the Virgin blog.

"Virgin Galactic is a bold entrepreneurial technology and is driving revolution – bitcoin is doing just the same," Branson announced on CNBC, admitting he also held bitcoins of his own.

Branson has a penchant for publicity stunts and accepting bitcoin is undoubtedly one of them. But the fact that bitcoin is now worthy of mainstream media attention for an already well-known business might be a story in itself.

Riders Borja and Elvis took on a task that would be daunting even with a suitcase full of US dollars: an epic motorcycle journey from Morocco to Cape Town, stopping in around 16 different African countries along the way.

The fact that they decided to fund the adventure at every stop by trading bitcoins with locals made the challenge even more impressive.

The duo were sponsored by LocalBitcoins, who have done much to bring bitcoin into the physical world by making face-to-face trading simple and accessible. The company also provides the most popular form of bitcoin trading in countries where bank transfers are difficult or impossible.

The couple converted their salaries to bitcoin when prices were much lower, and have traded their bitcoin for local currency at every stop.

So far, they've had problems with the bikes, seriously muddy roads, storms and intermittent internet access. They've stayed in cities and jungle huts, and learned a lot about Africa and its people along the way.

The biggest hassle they've encountered so far is having only bitcoins to offer as bribes to local officials along the way. Governments of all kinds, it seems, are addicted to fiat currency.

Having proved bitcoin's tradability even in places like: Burkina Faso, Mali, Senegal, Western Sahara and the Democratic Republic of the Congo, Borja and Elvis have passed through Namibia in the continent's South West, and are now in the final stages of their tour.

They're recording their trip on the LocalBitcoins blog.

There are plenty of things you can do with bitcoin but, let's face it, unless you were eating in certain cafes or buying everything with gift cards (or motorcycling through Africa), it was still tough to survive on bitcoin on a day-to-day basis in 2013.

Newlyweds Austin Craig and Beccy Bingham-Craig took a plunge bigger than most when they decided to live, and tour the world, exclusively on bitcoin.

Paying their fortunate landlord a 10% premium to accept bitcoin rent to make sure they had a home to return to, they headed off to three different continents to test how friendly the world really was outside bitcoin forums and discussion threads.

They raised over $70,000 on Kickstarter to document their journey on film and traveled between July and October, meeting with bitcoin enthusiasts at every stop and spreading the word to local businesses.

It wasn't easy, and the couple claimed to have spent less money in total thanks to limited spending opportunities.

They booked all their flights and accommodation through SimplyTravel, a German company which accepted bitcoin for its services.

Austin and Beccy are now back home in Utah, and say it's a relief to be able to use dollars again. While the bitcoin world salutes them for their efforts, it seems they were just slightly ahead of their time.

Question: In 2013, what went from 50 in March to 900 in November? Answer: the number of meals served to homeless people per week by Sean's Outpost in Pensacola, Florida (also the value of bitcoin in US dollars, but that's another story).

The charity started accepting bitcoin on 17th March, and has been a constant source of good news since, becoming what is probably the world's most famous bitcoin charity.

It also has a new project called Satoshi Forest, a nine-acre live-in agricultural property for its clients designed to be fully self-sustaining in future.

For Christmas, Sean's Outpost organized a "bitcoin angel tree" with a list of gifts donors could purchase with bitcoin. The list of nearly 40 items was fully funded within three hours.

In another Christmas twist, Bloomberg's Matt Miller accidentally exposed a wallet private key in full HD on TV. The money (about $20 worth) was instantly 'stolen' by Reddit user milkywaymasta who, given permission to keep it, donated it to Sean's Outpost.

Bitcoin's philanthropic spirit remains almost as robust as its late-2013 market value.

Overstock.com CEO Patrick Byrne took many by surprise in mid-December when he announced, almost casually, that the company would start accepting bitcoin as a payment option in 2014. Given Byrne's political leanings and opinions on fiat currencies, his company might be a good fit for bitcoin. Overstock.com (or O.co as it is becoming known) would be, however, the largest and most prominent company to introduce a digital currency option for all purchases.

Byrne said the company hasn't decided on a payment processor or thought about the tax implications much yet. Whatever challenges Overstock.com faces and/or overcomes, other merchants will be watching with interest.

Snoop Dogg

 and Mel B roared back into headlines and social media feeds at the end of 2013 with promises to accept bitcoins for their music.

Snoop tweeted that his next release would be "available in bitcoin and delivered in a drone", while (the former Scary Spice) Melanie Brown took more definite steps, partnering with mining operation CloudHashing and payment processor BitPay. Mel put bitcoin front and center on her homepage, where her record is now available.

The internet has historically been kind to celebrities who've embraced its new ways of doing business, so if the two continue with their interest in it, bitcoin could be set to revolutionize another industry.

Virgin Galactic image via Shutterstock