Tricky one for me was working out how quickly blood gets pumped out of a severed femoral artery (for a dream scene) - not much information on it surprisingly. Had to work it out from the time-till death figures and the amount of blood loss until death-figures.
I was also looking up various stages you go through before bleeding to death... grim.
Actually, most of the things I look up are medical related, either whether you can dislocate an elbow, how to relocate a shoulder/how bones get healed and various osteoporosis-type degenerative bone diseases.
That and I spent a few nights trying to calculate a sensible 100 year - 5 year (on board) space flight, lots of searches involved. I had to give up calculating things eventually, special relativity really doesn't work well with acceleration.