Thanks to lawsy and, I use the improved mk4 extruder.  I printed pyrophreek's modification of the fan for 40mm

http://www.thingiverse.com/thing:88660

But this runs into the Y-axis bolts at the front of the printer, I had to cut huge holes in it to get it to fit, and I had to wrap tape around the end to divert air flow from the print bed.  Is there a fan with a lower profile out there?

I made a very minimalistic fan mount and hot-glued a 40mm fan to it. I noticed that with the duct there was actually very little air coming out of it.

This shape mostly cools down the peek barrel, but you can play around with the angle at which the fan is held (I'm attaching the FreeCAD source).

http://www.thingiverse.com/thing:88660

But this runs into the Y-axis bolts at the front of the printer, I had to cut huge holes in it to get it to fit, and I had to wrap tape around the end to divert air flow from the print bed.  Is there a fan with a lower profile out there?