I have noticed that rapidly triple-clicking a folder in Tiger opens your chosen folder's window, and then returns you to the orginal folder you first clicked on. This works even if the folder's window opens on top of the original folder you triple-clicked. In practice, it appears to work as an 'open window behind' command.
This only works if the window you open has a lot of icons or you are using a picture as the background pattern for that window, so I supect it is a bug of sorts to do with timing issues.
[robg adds: In experimenting with this, I was able to make it work with a variety of folders -- even those in column view with only a few items. Still, I agree with leeww in that it appears to be some sort of a timing glitch. Since I use OS X in single-window mode, I was using Command-triple-clicks, which also worked just fine. I also tested this in 10.3, and it works the same way there.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20050922180200600