As for computer fans, you can get them up to 360mm in size, but the most popular of the larger fans is 120mm (popular among computer users, that is). And I must say wow! I just looked at the CFM ratings on these 120mm computer fans; I never realized the CFM's were so good. One 120mm computer fan, rated at 133.60 CFM. I never would have thought they'd pull that much air.

Either way, here's a link to that fan:
Newegg.com - Scythe DFS123812-3000 "ULTRA KAZE" 120 x 38 mm Case Fan - Case Fans
(if the link doesn't work, go to NewEgg and search for DFS123812-3000)

Anybody heard of running a small carbon scrubber with these small fans?