Found another great tip today. It is generally known that I do not like (Macromedia) Flash. Most important reason for this is the abuse of Flash by a lot of 'designers' and the use of flash for irritating ads as banners. (Another reason is the availability of an open standard) for vector graphics.)
Blocking Flash is rather easy (just do not install the plugin), but sometimes not 100% satisfactory. It would be better to select on a per site basis if you want to see the Flash or not, because sometimes Flash can add value. For example for a game or a movie, made by a developer with a clue.
Now I found a solution by Jesse Ruderman which I prefer. When a page has a Flash element, it shows a small link, and when you click on the link it shows the Flash object. Easy but effective.
To do this you must have a browser which supports user stylesheets and XBL (mainly Mozilla and family).
object[classid$=":D27CDB6E-AE6D-11cf-96B8-444553540000"], object[codebase*="swflash.cab"] -moz-binding: url("http://vorm.net/flash.xml#obj");