Quick UnZIP is an unzip plugin for standard Windows Mobile File Explorer.
After you install QuickUnZIP, you'll be able to open zip files as they were folders - you tap a ZIP file and view the files inside
PictureGZIP allows you to compress JPEG images from your PocketPC camera in real time. Each time you take a picture the program then GZIPs the JPEG image and places the GZIP file in the 'PictureGZIP' subfolder. The GZIP compression/ decompression is from Gzip
JPEGator is a .NET class library that can be used to compresses and decompresses JPEG (.jpeg, .jpg) images from your C# or Visual Basic applications using .NET Compact Framework. It also allows creating thumbnail images from large JPEG files using a minimum amount of memory (depending only on image width)