I used to have a setup where StumbleUpon was permanently on my TV set, and the Stumble button itself I had hooked up to my remote control, so I could stumble my way through things on the couch. It was infinitely better than TV itself.

I agree with other commenters how it expanded their online world, and I'm saddened that there is no real alternative to this now, especially in the land of insular internet bubbles we live in today.