Yahoo is starting to offer older disused usernames up for reuse, and allowing potential owners to pay $2 for alerts when a username expires.
The new Watchlist will allow a user to monitor up to 5 usernames, with e-mails automatically sent when any names on the list become dormant in a three-year period. Usernames will also be held for 14 days, giving the Watchlist user time to register without added competition from other potential username owners.