I don't know if you already know about the Give Away Of The Day site, but every day you can download a free software product. The only condition is that you must "activate" the product within the 24 hour download window.

Software developers gain from the feedback they recieve from the folks who download their products and obviously they also get the opportunity to offer upgrades and to build their lists.

End users get great software a no cost and the site owners enjoy lots of traffic.

It's an interesting model and something that I intend to test for myself.