I'll butt in here....
I had a 12g nano for a while, and with a mini mite and two additional 13w PC's, my tank got hot.
I went to the RadioShack.com store (formerly tech america) at 285 and Buford Highway.
I picked up two micro fans and a 12VDC supply for not much money. A little creativity and some metal brackets was all it took to attach these to the canopy.
Radio shack still has micro fans - matter of fact, check out
http://www.radioshack.com/searchsku.asp?find=273-240
(if that doesn't work, its part number 273-240).
They're great fans, and the best part is, they're only 1.57"x1.57"!!!
JJ