Sprint

[edit] Question: If I get a new phone from Amazon, eBay, etc., how hard is it to activate it?

(I asked the nice guy at the Sprint store, on 2007-09-14)

He said it was super simple: just bring the phone in and they'll activate for me (and, one assumes, deactivate my other phone).

And that doesn't require renewing my contract or anything?

Correct. No contract renewal required.

Hmm, it looks like you can even do that over the Internet maybe, according to [1]!