I don't see this mentioned to much on this forum. I know most people know the bennifits of them in your compost. Even though I don't know exactly what they do I do know they are a good sorce of N and can really get your compost pile cooking.
I recently learned that Starbuck offered them. There is one of those just a few buildings away from where I work. So I went in and ask and again and again and every time they were already picked up or they didn't have any. After about 10 times I got frustrated. All this and I came to realize they are just right under my nose with out walking to a starbucks. My office drinks coffee just like almost everyone elses. So I took and ice cream bucket and put a little note on it stating what these were going to be used for. WHAM! I got me lots of used coffee grounds. I now have two buckets one on each floor of my building and take home a good hall every day. I've never had such a cook'n compost before.
I just wanted to point out that people are very helpful are most are willing to help the enviorment if given the opportunity and ease. In doing this I also found out that my new company has a "green team" and I was invited to be a part of the team.