Also,
http://XwwwX.XheadXstashX.org (remove the X's to access). It's one of those thousands of popup sites. Of course, the content isn't all that wonderful, and turn your speakers off. But, it's a good test nonetheless. Just be careful with it.
Again, remove the X's from the url to access it.. to prevent accidental clicking.
* edit: Just in case you didn't realize by now, the link is NOT safe for work, although, it does provide a good pop-up test. I've tried my best to make this not "accidentally" clickable. Mods, if this is a problem, please delete.