LibOnionRoute

Library to make your software be able to use the Tor network out of the box. For instance if you want your browser, IRC or any other application reach an .onion address. You can also use it to reach normal servers hidding your IP number. It is basically an Onion Router modified to be embedded into your application. It is based on Tor sourcecode so is very much up to date and is easy to add code comming from Tor sourcecode.