Audioengine a5
From amazon for 325: http://www.amazon.com/s/ref=nb_ss_gw/002-1440759-0940014?url=search-alias%3Daps&field-keywords=audioengine+5&x=0&y=0
Review here:
http://www.audioholics.com/reviews/speakers/lifestyle-desktop-and-portable/audioengine-a5/page-2
It also seems that Axiom has gotten into computer speakers as well with their metal cone speakers and tweeters ... this is gonna be interesting i'd like to see a head to head review against the A5 seeing as how their selling for the same price if you go for the charcoal that is, no reviews on them yet, they've just come out.
http://www.axiomaudio.com/audiobytecomputerspeakers.html