Heres what to look for.
2 fans not necessarily big ones.
power from usb of laptop and not ac adapter
medium size, not small or large
adjustable fan speed a plus
find a cooler like this and it will bring down temps 5C
It's a bit spendy, but it't the one I plan on getting when I get around to it... I was having the same problems making the decision, and thats the one I found would best suit my needs.
I have a GPU cooling mod that I custom designed that will be manufactured by the end of May for an internal mod. If you want to send the system in I can mod the case too.
As far as simply a notebook cooler get a NotePal W1.
I will also be specially building a notebook cooler as "Phase 3 of my complete cooling solution.