Tumbl.in is a new service that mashes the concept of StumbleUpon with Twitter to help you discover interesting links from your twitter timeline.
My initial thought was that this is very a tad bit gimmicky but I was surprisingly happy to find how well the simplicity of the concept works. With Tubmlin, you can “stumble” (eh, tumble?) across links based on preferences that you select pulled from your twitter account. You can discover all links in your twitter timeline or filter by your twitter favorites or your twitter lists. This is particularly useful if you want to browse links posted by a specific subset of people you follow in twitter and cut through all the other noise.
According to TechCrunch, the project was started by @suchitagarwal and @thathoo at a recent hackathon event that ran in parallel with Disrupt. Will be interesting to see how this one plays out… hopefully, they will find a business model hidden in there somewhere.