Doesnt the internal fan work? If not you should check it out. Other than that, there are products I've been tempted to get from :
http://www.3dcool.com/?module=product&cat=12
There are USB equivalents of the same, but I wouldnt recommend it.
I used to see coolers that would go into PCMCIA slots, didnt find it anymore, hope u have better luck searching it out if you're interested.