Right now I am using the Carolina Bird Club listserve as a medium. It is well set up. Just some members are very passive-agressive so be careful about posting "rare" sightings. That sort of thing is better left to the local Mecklenburg Audubon listserve.
Right now there are not enough members for a listserve; I keep encouraging people to become members on the website so they can use the forum, which is useful.