I just found this out while playing with the 'option' modifier. For those of you who leave the trash warning on (like me), but sometimes know exactly what you are deleting, use shift-option-command-delete and the trash will be emptied without warning. Quick for the times when you want to get rid of a miscreated folder or something.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20020401001237315