[JKT]

It would be /.\*.gif I believe (at least that is what works for .swf).

However, the easiest way by far to block specific images is to control-click the image and select Filter Image from the contextual menu (it may be in the Image sub-heading). If you want to make it less specific, open the Blocked URLs list and trim back the automatically regexpressed URL to the level you want.

Edit: Made a typo (see later posts). This should have been /.*\.gif