I know most of us fly to our destinations before getting on a train or bus or boat... dunno about the rest of you, but while I'm happy to get a cheap ticket just about anywhere, I still want the best seat they'll give me. I've stashed years of flying experience into my noggin to pick the best airplane seats I can - when given the choice, but now I don't think I have to do the thinking anymore..
http://www.seatguru.com
It doesn't cover every airline in the world (hell, not even every airline to service the US) but it has a pretty good selection of airlines and their planes, along with detailed seating charts and ratings. Pretty handy