I signed up for the new TiVo Rewards program where you get points if someone buys a TiVo and gives you as the reference. I'm signed up under the email 'tivo at megazone.org'. (Obviously formatted correctly, just don't need spam bots harvesting that.)
If I had credit for the people I've referred in the past I could have a free 140 hour box. :-) Unfortunately they don't do retro-active points.
And if you have one, or are thinking about it, check out tivolovers.