Here is a trick to resize images in Photoshop using the scroll wheel on your mouse...in the Image » Size Image dialog, just scroll the mouse wheel. As you do, the figures in the size box will increase or decrease, depending on which way you move the wheel.
[robg adds: This works in CS2 and CS3, though I can't image that it's really all that useful, as it's tough to be precise. On my Mac Pro running CS2, this also caused lots of rainbow beach balls as I moved the mouse wheel. A friend with CS3 reported no such issues.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20080311131536460