There are plenty of Excel tip collectors out there (like say, exceltip.com), but I just came across a great (and compact) compendium of shortcut keys from Aabservations that taught me to do some things that I thought Microsoft had rendered impossible. One of my favorite new tricks is to press shift-tab after I've selected a block of cells. That immediately takes me to the bottom right of my selected block so I can make sure that I've selected the appropriate range. Also, I knew that ctrl-D could be used to fill a series down with a specific number, but I didn't know that it could also be used to fill in patterns (namely: 1,2,3, etc.).
So check it out--pretty soon, you'll be flying mouseless around your data.