gmail should suffice.
i like to use
http://www.guerrillamail.com/ when I need truly disposable emails. They work great for signing up to random shit that requires an opt-in (which will probably spam the fuck out of you later). Or to signup and take a quick look inside a forum/members area that requires a signup you're weary about.
Also works well for account creators, but I prefer to just setup a catchall on my own hosting for this. Seems to work best that way.