Earth Etc. makes a free wavelet based compressor that somehow ties in with their web server product. In theory they supply plugins that you can use to view the compressed images.

DCL reader JJB had this to say: Limited in size and other features in the free version as well as limited documentation in the free version, but decent examples if you can learn from those (you just can’t learn what they don’t show there). Very specific to Geo-Spacial images (satelite images and the like), decent compression, speed and recovery of all sizes equal to or less than original (use power of 2 sizes for best results)..

http://www.earthetc.com/iws/Products/dataprep/ecwcompress_text.htm