Note that the below are provided as-is, without any warranty. I personally find it convenient to use these in conjunction with the excellent Quicksilver application. Many of the scripts are slight modifications of others I came across online; now that I'm making them public, I should probably re-find and cite those original scripts. If you would like to contact me with any feedback, please email isherman at netzero dot net.
For those interested in using these with Quicksilver, the easiest way to do so is to just type some letters from the script name until Quicksilver finds the right thing (make sure the script file is in a place you have configured Quicksilver to search!). If you want to add a keyboard shortcut to the script, here is one way to do so: