Bitcoins might seem new to much of the "mainstream" economy, but some businesses outside that realm have already found good reasons to try out the digital currency.

In particular, the perception of greater privacy in bitcoin transactions is appealing to online businesses that deal in erotica, porn and other "adult" forms of paid entertainment.

For example, Blue Blood, which runs a network of counterculture erotica sites, has begun accepting the currency.

One half of a bitcoin buys a full year's mega-pass membership to Blueblood.com and its associated sites, which claim to celebrate "the best in iconoclast sensuality." The punk and goth porn site is also giving out free t-shirts to its first 100 bitcoin users.

MetArt, a high-end porn site, has also announced that it will be taking bitcoins in payment. It says it will accept bitcoins for access to its network of websites, which are offered on a 30-day basis.

The two porn networks join a host of other adult sites that accept bitcoins as payment, including sex-cam site TalkSugar. Bitcoin is more anonymous than traditional online payment mechanisms such as credit cards or PayPal, which makes it more appealing to people who want to hide sensitive online purchases.