This is the first Sparkfun product that did not work for me. It did not have much sticky. Maybe its too old? I use screws and heatsink grease instead. It was a pain.

I used four squares of this to stick a 4"x4" square of aluminum flashing to my Makerbot's heated build platform.
Works marvellously (surface temperature greater than 90C) and I don't have to worry about the extruder nozzle bumping into bolt heads anymore!

Alright, so how much better is this than double sided Scotch tape? $4 for that tiny square makes me cringe.

This stuff works great. I was able to cut one of the squares into 4 pieces and use them for some MosFETs that I mounted on a large heat sink for a SMPS.
The only downside is that if you burn something up and need to replace it, things get really messy.

I assume you can't use heatsink compound with this. I guess it's good if you need electrical isolation that badly... but for normal use, I would just use the good old bolt technique.