This is a slightly biased posting (since I own the company I'm talking about), but I've had various volunteer groups celebrate the accomplishments of a volunteer or leader by using a service called LifeOnRecord Events. The way it works is that a toll-free number is given out to fellow volunteers, and other people the volunteer has touched. People call in with stories of their favorite moments of time spent with the volunteer, favorite memories, or well-wishes. All the recordings are compiled onto a keepsake CD. The website is http://lifeonrecord.com and we have special pricing for volunteer organizations. I'm the owner and you can contact me for more information.
Alaa El Ghatit