[see other comment about forum being hacked]
Certainly useful for Ubuntu. Also can be useful for Debian, Ubuntu derivatives (LinuxMint, for one), other Debian derivatives, Linux in general, and PC hardware.
As with any advice from a forum, be sure you have a back-up (or at least a recovery plan) and read the docs if you are unsure about the commands or instructions.
Not a rating, just news. Ubuntuforums.org has been hacked as of 7/20/2013 and still down 7/22 1000 UTC.
Change your passwords.
Partial quote from website follows.
Ubuntu Forums is down for maintenance
There has been a security breach on the Ubuntu Forums. The Canonical IS team is working hard as we speak to restore normal operations. This page will be updated regularly with progress reports.
What we know
Unfortunately the attackers have gotten every user's local username, password, and email address from the Ubuntu Forums database.
The passwords are not stored in plain text, they are stored as salted hashes. However, if you were using the same password as your Ubuntu Forums one on another service (such as email), you are strongly encouraged to change the password on the other service ASAP.
Ubuntu One, Launchpad and other Ubuntu/Canonical services are NOT affected by the breach.
2013-07-20 2011UTC: Reports of defacement
2013-07-20 2015UTC: Site taken down, this splash page put in place while investigation continues.