The foaf:aimChatID property relates a foaf:Agent to a textual identifier ('screenname') assigned to them in the AOL Instant Messanger (AIM) system. See AOL's AIM site for more details of AIM and AIM screennames. The iChat tools from Apple also make use of AIM identifiers.

See foaf:OnlineChatAccount (and foaf:OnlineAccount) for a more general (and verbose) mechanism for describing IM and chat accounts.