TivoTool is a pretty cool new app for managing your TiVo video on the network through a nice OS X GUI application. There aren't a lot of TiVo tools for macs so this is a nice new development.
It's not for the faint of heart -- it does require some fairly sophisticated hacks to be running on your TiVo in order to download and stream video unencrypted, but if you've gone that far with your TiVo, this app gives you a nice TiVoToGo-like interface on a mac (there is also a command-line version that works with both mac and linux).
Check out the screenshots of it in action. The integration with iTunes is very impressive stuff and being able to transcode video or send it to iMovie is an added plus. Hopefully when TiVo releases an official TTG mac client, their app approaches the usefulness of this package, allowing users to save and view video directly in iTunes (and transfer video to future video ipods).