You're browsing the web and you click a link to an article on a site (let's say example.com) but instead of getting the article you get a screen asking you to login or register. Infuriated at the idea of pointlessly registering for yet another site you turn to your good buddy bugmenot.com
STEP 1: Make a note of the website address your are trying to access. For example:
STEP 2: Visit http://guppit.com/site/50a932086a
STEP 3: Enter the address from step 1 into the box and press the "Get Logins" button
STEP 4: You should now be presented with at least one username and password. Make a note of them.
STEP 5: Go back to the site you were originally trying to access in step 1 and proceed to login with the username and password you noted in the previous step.
With any luck you should be able to access your article now