I tend to collect a fair amount of images found on the web. I’ve found that the best way (for me) to keep track of these found images is by organizing them in iPhoto, part of Apple’s iLife suite. And, there is a great little time-saver built right into Safari.
If you right-click (or control-click) on an image in Safari, you can select “Add Image to iPhoto Library”. iPhoto will launch, and import the photo. It’s little features like this that keep me using Safari, rather than switching to Camino, or Firefox.