is to be found at
For those who don't know, Peartrees is a social bookmarking site much like del.icio.us, only the GUI is based on the tree metaphor, and it's a flash thingie. Personally, I like the idea of social bookmarking because it helps me find releveant content easier. The downside of Pearltrees is that all "pearls", i.e. links, are public, so you have to be careful about what to share if there is any crossover between your online persona and your real life identity.
If you're not signed up, you have to click on "Start Now" to see it.