Im surprised nobody is using Flashblock, its a great little addon to your browser that prevents Flash applications from starting or loading until you let them
So all those frikkin annoying Flash adverts don't even get a chance to start.
Instead of the flash starting you just get a play button centered where the flash app should be - if you then click on it the flash will start - otherwise it wont.
I use it a lot and its great.
You can get it here -
http://flashblock.mozdev.org/