Iconfu is an easy-to-use online icon editor and library for anybody who needs to draw or modify an icon but doesn't necessarily have the means (time/money/corporate approval) to use photoshop or something similar. It's dedicated to icon manipulation, so for example the drawing canvas is zoomed 16x by default so pixel-by-pixel editing is straightforward. The most common need is to take an existing icon and lighten/darken it or change the hue a little so it matches the theme of the target site, so the colour-levels tool is especially easy to access.
Iconfu provides a basic set of tools:
colour channel manipulation
pixel-by-pixel drawing
gradients and ellipses
full 8-bit transparency per pixel
upload/download as .png, .gif, .ico.
compose icons by layering new drawings, uploaded images, and library icons over one another
various drawing modes that allow colours and shape (transparency) be manipulated independently
undoable editing history (unlimited for paying users)
free for icons up to 24x24px
compose animated .gif images from editing history
http://iconfu.com/
