I don't have a two button mouse, but I do use -click often when I am browsing. A late addition to Panther (in Tiger as well) is that when you -click on an image, it gives this new choice of saving to the desktop, and and eliminated the "Save as..." option altogether (used to have "Save to Dowloads Folder" instead of "Save to Desktop").
I don't like this... I hate it that my only option is to save an image to the desktop (or to iPhoto Library). I can copy the image, open Preview and save it where I like, but that takes too long when I want to dl a bunch of arbitrary images one at a time. What I used to do is switch my Downloads folder in Safari preferences to a new image folder, and then I was able to quickly download what I wanted and have it in the exact place I wanted it.
Does anyone know how to reconfigure/customize the -click pop up window?
(This is something I was hoping MacWorld would put in there hints or tips and tricks columns, but I haven't seen it)