All well and good for product registrations and freebies but beware of using them on forums, etc.
I know a lot of webmasters use spam lists/db's (usernames, registration IDs, email addresses, email domains, etc., used by spammers) and these disposables are often on them and added to the spam blockers on sites and forums. (Mind you, I also know webmasters who won't accept online email domains, including Google, MSN, Hotmail, Live, Yahoo, et al.)
While the domain one uses may not be on the block list when one registers if it's added later and you still have that email in your profile you could lose access to your account. Bit of a bummer of you've become a regular.