Both this Japanese website, and a small group called Abracode make a bunch of very useful and productivity-based Contextual Menu (right-click) plugins for Mac OS X. All of the Japanese ones are Universal binaries (have versions that are, but also have PPC-only versions), but some of the Abracode ones are PPC-only and therefore won’t run on Intel macs (that’s just how Rossetta and plugins work).
The Japanese ones include many for Finder relating to file management. These include visibility, DS Store/ fork management, and file info (as well as many others). They also make a <em>very</em> useful one that puts Apple's Script menu into the Contextual Menu. The Abracode ones (which I'll admit I had installed months ago before I had a MacBook) include a handy Clipboard manager which supports as many clipboard content sets as you'd like (and can optionally secure any one or more of them on your keychain). They also make a file manager and resource fork deleter as well as an encoding/ decoding tool for MacBinary III files. The one <em>very</em> intriguing Contextual Menu Plugin that Abracode makes is one that allows you to manually customize extra items that run Applescripts, or various kinds of shell scripts, and can have their own NIBs attached. I haven't installed it because it will take a while to properly set it up the way I'd want it.
Abracode also make a plugin to add a keyboard shortcut to any item, including Apple’s built-in ones. That plugin simply isn’t needed by me at all. Enjoy, Alex.