Normally I wouldn't create a tip to tout a bit of software, but this one is too good to pass up. It's a tiny clipboard history manager named ClipX. Instead of alt-tabbing back and forth between windows copying bits and pasting them you can copy everything you need and then alt-tab over and ctrl+shift+v and hit the number of the entry you want to paste.

Link: http://www.bluemars.org/clipx/