I entered ‘deaf’ as a search term for groups in Second Life this morning, and here’s the result (I’m not assuming that this list necessarily reflects what all deaf people are doing in Second Life as that would be daft).
BSL user group (4 members)
ASL user group (14)
SFCSLQ-PCLO (3 members) Starfleet Command Physically Challenged Liaison Office. A group working to ensure that everyone can ‘equally enjoy the same experiences as other Starfleet officers’.
SL Deaf Underground (78 members). An ASL and Deaf Culture group.
Anti-Voice in Second Life (11 members) ‘For whatever reasons we don’t want voice in SL […] Maybe we’re deaf [or] maybe we don’t want to hear people piss and moan about lag all the time’. Fair enough.
There was another listing or two that mentioned ‘deaf’ or ‘deafness’, but these seemed to be the pertinent ones.