BugMeNot is a site dedicated to providing usernames and passwords for (m)any websites. It's a great way to avoid logging in. However, it's sometimes tedious to check every time whether there is a login available or not. I am not sure I really save that much time going to the website each time and trying to locate a working password. Luckily there is a solution!
BugMeNot Extensions for Firefox and Chrome!
Checkout Chrome Version in Action:
My personal opinion is that the firefox extension is better. You simply right click on a username field and say 'Login with BugMeNot' and voila! It also allows you to go back, try another account, choose an account and report success/failure rates.
Bonus Tip: Mailinator - disposable email accounts for things you want to register for once and don't ever want to be contacted by again.
