If Flash ads annoy you, but you don't want to go so far as to uninstall flash, try jTFlashManager. It allows you to enable and disable the Macromedia Flash plugin without having to uninstall. The browser can't find the plugin if it has been renamed, so the the program works by simply renaming the Flash plugin back and forth when you turn Flash on or off.
I have it pointing to the npswf32.dll file in the Mozilla\Plugins folder.
You can also block every plugin on the page with a simple bookmarklet:
Just copy this line and place it in a new bookmark. When you're on a page with an annoying Flash animation just select it and it will be gone in no time.
How can I adjust the flash so it can't loop? We are running terminal server, and the large flash ads that continuosly loop are killing me via dial-up. I don't want to unistall it, just prevent the endless loops from eating my CPU cycles up!