Well...maybe you can't get really tiny computer fans in 115V...but you can certainly get them in about 4" diametre.
Check out RP Electronics....Look at the fans they have available and you can choose from a good variety of air movements and they all connect to 115V directly. (just plug them in!)
You can even choose the 230V ones. If you plug those directly into 110V, they run at 1/2 speed and are especially quiet. If you are going to do this, you have to purchase the ball bearing type otherwise they may fail to restart when stopped. (Mine never have, but that is what I understand)
http://www.rpelectronics.com/
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400 gal reef. Established April, 2007. 3 Sequence Dart, RM12-4 skimmer, 2 x OM4Ways, Yellow Tang, Maroon Clown (pair), Blonde Naso Tang, Vlamingi Tang, Foxface Rabbit, Unicorn Tang, 2 Pakistani Butterflies and a few coral gobies
My Tank:
http://www.canreef.com/vbulletin/showthread.php?t=28436