Gosh, it’s been almost 3 years since Google bought GrandCentral and transformed it into Google Voice, a service that lets you set up a phone number that can ring multiple phones. It’s been invite-only ever since, but today Google opened up registration to public. (U.S. only, sorry.)
You can do lots of neat stuff with it, including forwarding calls to different phones based on who is calling you.
Personally, my favorite feature is voicemail transcripts. They’re not perfect, but when someone was randomly calling me and speaking Icelandic (during that whole volcano air travel clusterf*ck) — my god were they funny.
Google Voice For Everyone [Google]