The Berkeley Public Library maintains a tool-lending library open to all residents and property owners of Berkeley. The library lends out everything from cabinet scrapers to rotary hammer drills to portable workbenches (!).
(via Make)
Update: F_D sez, "Burlington, Vermont's Fletcher Free Library has a similar program with garden tools etc."
Update 2: Lexica sez, "The Oakland Public Library also has a tool lending library, located at the Temescal branch."
Update 3:
Thom sez, "There is a tool library in Portland, Oregon too.
Update 4:
Corey sez, "I just became library administrator of the Thompson Public Library in Thompson, Manitoba, and we also have a tool library. The Tool Library has been used for over 2 years now, and has really come in handy."