Bins is a taskbar manager for Windows 7. With it you can organize your icons into, well, bins, effectively shoehorning four programs, links, or whatever into the space usually occupied by one icon. Take a look:
The program requires Windows 7. After installing it, just drag any taskbar icon onto any other taskbar icon. This will produce a little popup area--the "bin"--into which you drop the icon. Repeat the process with other icons, adding up to four to each bin you create.