Help: trying to remember the name...

I have been trying to remember or find out the name of this piece of software, and I can't at all, which is annoying. A couple of weeks ago I remember reading about it on one of the mac sites, and thought it would be worth installing and giving it a test run when the new computer got here. Now it's here, and I don't know the name. Anyhow, as far as I can remember, or could tell at that point, it's a replacement for the finder, or maybe not a replacement, but more of an object-oriented UI that replaces the folder/file analogies of the finder. I think it might begin with an S, but I could be wrong. Any help would be HIGHLY appreciate.