The latest version of TiVoToGo, TiVo's software for your computer that lets you transfer TV shows from your Series2 TiVo to your laptop for later viewing, can now transfer your shows to your video iPod or PSP, and can burn shows to DVD. Those new features will cost you $25, but there's still a free version without them.
TiVoToGo is only for Windows, not for Mac, but guess what, Macs run Windows now. TiVoToGo runs pretty well in Parallels Desktop running Windows XP. You'll need an MPEG-2 decoder for Windows Media Player to watch videos, and I'm guessing most people get one with their video card, but not with Parallels. The easiest way I could find to get an MPEG-2 decoder was to just pay TiVo the $25 for the upgrade. That worked.