GIMP image sizer
The link below provides you with a script you can plug into GIMP which will let you easily shrink an image for PDA or whatever. Microsoft actually has a more convenient tool under its "Power Toys" category but I find that sometimes does not work. So I still use this at times. Copy the script below into a GIMP folder that looks like this:
C:\Program Files\GIMP-2.0\share\gimp\2.0\scripts
Start GIMP and the script should be available in your script-fu menu (check both script-fu menus: the tool menu and the image window.)
Why use it? Because normally to shrink an image to fit within certain size limits it takes a few steps: 1) determine which is larger: width or height 2) choose to scale the width or height to the new size limits 3) save image.
Now I simply link the script with ctrl-F1 and that is all done for me automatically.