Opera Software has made their browser free, in the Eudora sense. Basically, you can use the browser for free if you’re willing to let them display ads in the interface, or you can pay up and get rid of the ads. I’ve been using the sponsored mode in Eudora to read my email for awhile at work, and I think that it works pretty well. In other words, the ads are easy to ignore. The only problem was a bug in the ad code that caused Eudora to crash every time I launched it until Eudora released an upgrade, but that’s a problem with implementation, not design.