as stupid as it sounds, i tend to just hit a site like http://www.codango.com/ and browse around...if I see a script idea that seems interesting, but feel its something I could recreate in a more effective manner in some way or other...I go after it. This makes you learn some n ew stuff while really analyzing the end result based on usability and practicality...just a fun little excercise for me personally.
Now, inarguably, I could have time much better invested if I would just focus on a bigger project of some sort...but I tend to be too easily disinterested after a while.
Good luck in your quest.