Andy Szybalski has released Shellsilver 1.0, a Mac OS X tool that lets you execute UNIX shell scripts directly from the Finder.
You execute the scripts by double-clicking on them. When a file with the extension .sh is double-clicked, Shellsilver will launch, and a Terminal window will pop open, executing the shell script.
Shellsilver is freeware; it’s a 72K download. You can also download the source code (a 3.5MB file). Shellsilver is a Cocoa application written in Objective-C.