I've been contemplating the same kind of project myself because I keep filling up my VMUs and having to delete game saves to make room for new ones :x . It /might/ be possible if you used the same kind of memory the VMU uses though you'd probably have to set up some neat kind of switching mechanism ...

I was just scaning over the boards and ran across this topic. It's easy, just grab a 12V fan out of a computer (power supply fan is what I used), then run wires from the DC power board out to the fan and presto! :D Its not mounted and it's not the prettiest, but it works.

Hope this helps!