Emptying the trash in iPhoto!
I had a tip previously about emptying the Finder trash with the keyboard shortcut "Command - Shift - Backspace". It is really fast when you are cleaning up files and folders in the Finder. What you might not have noticed is that the same can be done in iPhoto. iPhoto actually has its own trash where deleted pictures end up. I guess I just wasn't used to it, but the pictures simply accumulated there and I always forgot to empty it. I find the "Command - Shift - Backspace" much easier to do after deleting a bunch of pictures.