I recently wrote a tfs server plugin that creates new builds automatically whenever you add or branch a solution file. It's fairly simple, but worth sharing.
It takes advantage of another piece of code I had previously written (or perhaps found online, I honestly can't remember now) to create builds using the TFS api.
Installing it is very simple, just build the class into an assembly and copy it to c:\Program Files\Microsoft Team Foundation Server 11.0\Application Tier\Web Services\bin\Plugins you may also need to copy a couple of the referenced dlls to the same folder.
