Clitter is an AppleScript Studio wrapper - frontend - Cocoa GUI for the open source tool convertlit. It converts Microsoft's propritary eBook-lit file format into normal html files which can be opened and read with any OS X webbrowser.
Clitter is freeware. You use it as it is and on your own risk. It has been tested under Mac OS X 10.4 on a PPC and a Mac Intel machine