Most are probably familiar with XiaoXiao's Stick-Figure Fighting Series.  Movies 3, 4, and 5 are my personal favorites; Movie 3's a golden oldie -- brilliantly choreographed, and reeking of pure adrenaline.  Movie 4 is actually interactive, and plays like a nifty arcade-style shooter. (Remember, the space bar reloads!)  And Movie 5 has lots of raw energy, but somehow ends cute.  ^_^

Movies 7 and 8 -- part of a continuing series -- are worth checking out too.  Fans of stealth will enjoy Movie 7 in particular. :)

(Blast it, I clicked on THREE wrong links before finally hitting the correct one to reply...)

Aww yeah, XiaoXiao.... Man, I haven't visited Newgrounds in some time, heh.