I recently went through my weblogs and noticed a bunch of leechers hotlinking to one of my sites (WiiLoveMario.com).  After some Googling, I found a little peice of code that will thwart all hotlinkers.  All I had to do was create a .htaccess file in the directory where the files were located and added the extensions of the files that I didn't want to be hotlinked.
 
Here's the code to add to your .htaccess file

Well, since you're here. This site is for me to vent about everything. :)