Robin Good: Tilen is a free downloadable software for Mac and PC that allows you to easily slice any image into any number of image slices all saved separately.
Tilen can save tiles in JPEG, PSD, BMP, PNG, TARGA, or SGI formats, and open many more.
Tilen will run on Mac OS X 10.3.9 or higher, or Windows 2000 and higher. Tilen requires Apple QuickTime to be installed. Tilen runs natively on both PowerPC and Intel Macs."
Free to download.
More info: http://www.nasolab.com/tilen/index.html