I enjoy photoshop, you can setup a script to do the work for you.
Open a photo to resize.
Go to the action menu
Click to start a new script and name it (recording begins automatically in CS3)
Go through the process of changing the size and saving the file (overwrite the file). Once you've finished and the file is saved, click the stop button i nthe actions script to stop recording.
Then go to File -> Script -> choose the folder of images, set the output folder, style, etc. Select the script and run it. Will resize your scripts, not super fast and I'm sure there are better ways.
Personally I just use the feature of my website to resize them as I upload them (I get the option of choosing original size, 1024, 800x600, 640x480, or custom) and then host from there.