Ace free jpg (etc) cruncher.
This is an excellent wee, free piece of software. At it's normal setting I can reduce a jpg photo to a great quality thumbnail and reduce the file size 30X.
Any web developers, I would suggest you have a look at this. Anyone just interested in reducing filesizes dramatically will also like it.
It really is the bees knees.Easy Thumbnails is a popular free utility for creating accurate thumbnail images and scaled-down/up copies from a wide range of popular picture formats. An elegant interface makes it a snap to find your images and select them for processing individually, in groups, or in whole folders, using a simple file selector and built-in image viewer. You can use slider controls to rotate images and adjust their contrast, brightness, sharpness and quality, and check out the results with the built-in viewer.
Scale images up or down in batches
Nine resampling filters, including Lanczos3
Sharpen soft images from digital cameras
Real-time preview of target image
Supports the new JPEG 2000 image format
Preserves EXIF data in JPEG images
Supports lossless JPEG rotation
Free software producing quality results