BugMeNot

It saves some websites the trouble of having to look up IDs on bugmenot and manually ban them on a regular basis. BugMeNot originated back when the NY Times and similar sites were free but required you to register (so they could market to you) to access content. When folks use BugMeNot for online forums that don't permit anonymous posters, it's generally for trolling and abuse, so I used to have to check it regularly before BugMeNot added the option of a website requesting to be excluded. From the site:

"Sites should only appear blocked here if they match one or more of the following criteria:

* Pay-per-view: users pay money to access the site

* Community: users register only to add/change content (but not to view)

* Fraud risk: user accounts contain sensitive details e.g. banks, online stores, etc"

Basically, bugmenot allows websites to opt-out when the main purpose would be for fraud, theft, or abuse.