The Humble Introversion Bundle — a pay-what-you-want compilation of the games Uplink, Darwinia, Defcon and Multiwinia — gets a huge upgrade today: the source code for every title and a bonus game, Dungeons of Dredmor.
Every buyer gets the source, but Dungeons of Dredmor is unlocked only if you beat the average donation, which is a piddling $3.71. Non-cheapskates also get a copy of Aquaria, worth the price of admission all by itself.
Also fascinating is the tech demo of Subversion, Introversion's recently-mothballed game project. It appears to be an implementation of this Siggraph paper on procedural city generation, and the video just sold me on re-buying a load of games I already own just to get access to it!