Microsoft Office Entourage Sound Sets is one of my pet features I added to Entourage a bazillion years ago. A sound set is basically six sounds that you can change so that when you get new mail, you can hear a duck quack or a clip from your favorite movie - “I’m in the pipe, five by five”. This feature was really fun to add, though generally I like my computers to be as quiet as possible so I don’t really use it. But today I’m working at home due to a sore back so I want Entourage to ping when I get a work email. I want a very quiet, short sound, which is why I dug this feature up again. I find the default sound to be too long and annoying.
Here’s a nice tutorial on how to make a sound set. And here’s a website with a bunch of free sound sets on it. Very cool. Go ahead download them. Annoy your spouses and coworkers. And think of me when you do it. 
Edit: I just tried one of these sound sets and Entourage doesn’t recognize it. Turns out the old sound sets aren’t compatible with Entourage 2008. You have to convert them. Here’s how. I find this to be disappointing (but I understand why they did this). I just can’t be bothered to convert over the sounds sets linked above. It would have been nice if Entourage converted them for you. To me this is a little thing that goes a long way toward pleasing users. There’s a fair amount of people who got bit by this.
Here’s some more info on Sound Sets in Entourage 2008:
Google Groups
Apple Support Discussion Group
An Entourage Blog posting
Erik Schwiebert posts about Entourage Sound Sets on arstechnica.com
Another long thread with people banging their heads against this
Sigh. I’m giving up. I can’t get it to work. How sad.
