Perhaps you are thinking of the Backserv and Backmed lists? Rather than donation lists, they are considered exchange lists, in that many donors at least request postage reimbursement in exchange for what they are providing to other institutions. Also, people post their needs if they have gaps in their holdings that they are trying to fill. The first list is for titles of all kinds, the second for medical.
I have been on Backmed for years, and I love it. The participants are terrific; I feel as if I have friends all over the country, although I have never met them in person. Although it is officially an unmoderated list, there is something of a consensus on how we proceed. In fact, one person recently gathered the main ideas and posted them to the list as guidelines. She did an excellent job!
Our "own" Birdie MacLennan (one of the SERIALST moderators) has a great web page with links to info. on how to subscribe to the exchange lists that I have mentioned and to others as well. Check it out!
THE CHILDREN'S HOSPITAL OF PHILADELPHIA
MEDICAL LIBRARY ROOM 9546 MAIN BUILDING
ATTN NATALIE L GORVINE LIBRARY ASSISTANT
34TH STREET AND CIVIC CENTER BOULEVARD
PHILADELPHIA PA 19104-4399
Phone : 215-590-2317
Fax : 215-590-1470
email : firstname.lastname@example.org