http://www.directory2l.com/

A search site keyed by keywords and categories, oriented around businesses. You can find businesses selling specific things here, but not specific objects or avatars themselves. It was fast but still lightly populated when we tried it. I'd keep an eye on this one!

http://www.sloog.org/

"Sloog is a bookmarking service for Second Life residents. It allows users to save favourite places and avatars and search for them later, both in-world with a simple plug-in (HUD) or via web browser at www.sloog.org"