I’ve seen it on several sites now, like Digg, Techcrunch, and Mashable (which also has an option to sign in with Twitter, however I think Facebook Connect is more valuable with the amount of info tied into your profile; Disqus we’ll discuss later). Now, the “Connect with Facebook” button is right up there with the Digg logo screaming “hey! please sign in. you can digg stuff. we know you have a Facebook account…”

Because it makes it easy, such a service aims to encourage more interaction with a site like Digg, where many go to view yet a small portion interact. In practice? Apparently it’s “increased registration by up to 300% for some Facebook Connect Partners” -Facebook (wish we knew which partners ;) So what is a user worth to a site? And also, what’s it worth to Facebook to be tied in to these sites as the “account provider”? I’ve been thinking about the new world of free lately, and I’m just starting Chris Anderson’s book “FREE” (free online, how about that) which I’m going to buy because I’d pay not to read a 288 page book on Scribd.

To be continued…both user interaction and “free” are pretty interesting topics so feel free to discuss! Join the conversation on Twitter, too.