No firefox install can be complete without the NoScript extension. It blocks all scripts from running unless you allow it. You can either put a website on a safe list or simply allow scripts to run for that particular session. It's selective as well, so you can allow a site to run scripts, but not allow all the rest of the garbage that's trying to runs like, for the website in this thread, lycos.com, realmedia.com, akamai.net.
Most of the time it's quite unecessary to let scripts run, as they aren't for your benefit. Occasionally I have to allow scripts in order to use drop down lists and some search functions.
So the result of using NoScript, along with flashblock......no dancing hampsters and no pop up, pop under. The net is such a nice peaceful place