Yahoo has added some very useful filters in their Image Search engine. For instance, you can specify dimensions (height x width) in the search query and it will display only pictures / icons that exactly match the size.
Yahoo recently introduced a web based tool called Smushit to help you optimize the size of web images without affecting visual quality.
vi.sualize.us (read visualize us) is an interesting web tool that lets you bookmark and save images or photographs that you may encounter on the Internet.
Learn how to hide any web image with some CSS code. When people open a web page containing an hidden image, all they see is some plain text - the actual picture is revealed only when they select the entire text with a mouse.