I'm not a fan of large frameworks that do all sorts of voodoo on my behalf. This framework is less than 1300 lines of code and includes
* a RESTful routing module that supports regular expressions
* a templating module
* a session module that supports native, APC and Memcached
* a caching module that supports APC and Memcached
* a config module that supports overloading of multiple config files
* a database module that supports PDO MySql and prepared statements
I've used it on publicitweet.com (sold), textbookrevolt.com and thescholarapp.com. It's got some good usage but I'd like to iron out bugs I haven't come across and let others use it if they'd like.