As Jon Udell has mentioned, there's a ton of data online, but it's not often we can find it, often hidden in the deep, dark basement of some website. He has proposed that people book mark public datasets on del.icio.us under the tag "publicdata". I think this is a great idea. In turn, you can subscribe to the feed with the url http://del.icio.us/tag/publicdata.
I've been doing this already for a while, but I had been just tagging with "data". So I'm going to join in on the party and start tagging with publicdata, and I hope others will too. Until sites like Many Eyes and Swivel get more wind beneath their wings, I think it's necessary.