Browsing the forum is certainly a good way to start - it is pretty easy to miss stuff when you don't know what you're looking for/at though!

My most recent "holy cr@p that's impressive" find were the threads relating to the transitions.ini file. The impact on menu navigation speeds achievable via tweaking this file has to be seen to be believed.

http://talk.maemo.org/showthread.php?t=43964