This is probably too large of a deal for anyone in here to bite, but figured it's worth a try. We're also pursing options elsewhere.
I'm a cofounder of Metaspace Studios, a social game developer. (For this discussion, Social Games means games that run on Facebook/Hi5/other social networks), and we're looking to sell a game engine. (Full source code and rights)
We've created an engine that makes very rapid development of text-RPGs like Mafia Wars possible. It's low maintenance, feature rich, and makes it possible to create games with different themes and some different features in as short as 1 month (that's how long it took us to build our last game, City Police Department, with code changes. With no code changes, two weeks tops)
Depending on the game, these can be extremely profitable. One game using the engine (City Fire Department) generates over 8k per month, with around 10K Daily Active Users. The game is sitting on a single server and takes around 1 mbit of bandwidth to sustain, so hosting costs for games on this engine are extremely low as well.
So why are we looking at selling? Our team is very small and having a hard time keeping up with content creation, it's taking more time than we'd like away from other projects. We're also strategy gamers at heart, and while this model is simple and profitable, we're looking to focus our attentions on richer games. If we can find the right buyer this will allow us to push forward with our other plans.
You can use this engine to build your own games, or license it out to other people and get residual income that way. This is actually the model we tried to roll with for a while, but we don't have the connections or time to go find clients. I'm sure there are people in here who can.
The engine has a full admin interface. Creating a new game is literally as easy as uploading images, entering in jobs, items, descriptions and a few other things, and pressing go. You can make code changes of course (several of our games have some unique features), and there's an easy system to keep track of which games get which features too.
For more information, please visit http://metaspacestudios.com/
to get a better idea of what we're talking about. You'd be purchasing the engine and sole rights to it.
The asking price is negotiable, but we're shooting for around 4200 BTC or the equivalent in USD. This engine represents many months of hard work and refinement, has already been stress-tested and , and has a proven revenue model so in the right hands you'd be able to recoup your investment fairly quickly.
If you're interested please PM me and we'll go from there, or post questions in here. Thanks!