Here's a simple AppleScript that I wrote that uses Growl to display the number of characters, words, and lines in a piece of text selected in Quicksilver (just copy and paste the code into Script Editor, and save in ~/Library » Application Support » Quicksilver » Actions).
Word/letter/line counting is a simple but useful function that I couldn't find anywhere else in Quicksilver, and it's is particularly useful for checking the length of Twitter updates before sending them using, for example, the Tweet action by Coda Hale, or this improved version with Growl support by Ted Leung. Thanks to Ted for the Growl notification part of the script that I adapted.
I hope people find this useful. Previously I'd echo my tweet through a pipe to wc and run as a shell command in Quicksilver to check the length. This action is a big improvement -- now Quicksilver provides my favourite way to update Twitter.
[robg adds: Note that any updates to the above-linked script will probably be posted in this thread on Quicksilver's forums. The one I linked to above is stored on macosxhints.com just to insure that it's downloadable in the event something does happen to the original post. As of today (February 12th 2007), both versions are identical.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=2007020801072114