I have set up "dummy" users on my machine that I use to try code and such when I don't want to risk breaking my "main" account. I came up with a nice easy way to share code, text, or the like between the users when switched via Fast User Switching (FUS).
Using SubEthaEdit (free for non-commercial use), you can use Rendezvous editing between users. Open SubEthaEdit and the document/text you want to edit (or a blank document for a new 'clibpoard'). Chose File -> Announce, and the user drawer should open to the side. Change the access control to "read and write."
Switch to your other user via FUS, and open SubEthaEdit. Click on the Rendezvous button in the toolbar (it may be off the right edge of the toolbar, and you'll need to click the arrow to get to the other toolbar buttons). Your other user should show up with a document under their ID. Double-click on the document, and it opens. Voila! Now both users are editing the same document.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20041117105730329