When OSX was first released, Apple moved the trash from the desktop to the dock, which upset a lot of people who found the earlier desktop trash more convenient*.
I first made Bin-it in 2006 to add a desktop trash to OSX, and shortly afterwards collaborated with Chris Knight to add a very quick and easy progressive indication of the trash level with a changing icon.
Built-in themes include the standard OSX trash (with added levels of trash) and for the retro look, pixellated OS7 and OS9 cans.
Here's how to add your own:
1. Prepare between two to six images, 128 pixels x 128 pixels with transparent background. Save in a format that preserves the transparency such as .png or .tiff
2. Go to Preferences > Themes and click the [+] button
More information and the latest version of Bin-it is available at http://peacockmedia.co.uk/bin-it, free for existing licence holders, or £4.95 if not.
* The big inconvenience of the desktop trash was that it was often covered with a window. Note that Bin-it allows you to choose its level: desktop, floating or 'keep on top'.