there is a add-on to Firefox called ImgLikeOpera that I always use. I keep pictures turned off at all times (except some filters that turn them on for sites like YW) and I can right-click individual pictures to show them, or click the button on the toolbar to show all pictures from the current site. It’s a great add-on and I highly recommend it to all who use Firefox.
I also recommend using FlashBlock which makes Flash objects show up as play button that you have to press to activate. This stops Flash videos from playing automatically.