If you need routines to resize images on the fly, then you may be interested in what I have written.
On my website, I have a gallery section. http://www.clubclimate.com/gallery
How I add pictures to the gallery is upload all the images to a folder, Then I run a script that takes these images, resizes them to thumbnail size, then saves the thumbs in a directory. The site then uses these images to automaticly link to the main image.
The script can be configured to resize to any size needed, and can be configured to suite any need.
Please contact me if you need assistance, or a custom written script anand@clubclimate.com
Cheers, Anand