If you are using Jive Apps, it sounds like you could use App Data. If not, you could try the User Properties Map, but not sure if that is manifested in the REST API or not. Mark Weitzel may have some thoughts.
In addition to App Data, I'd check out OpenSocial's data context. It sounds exactly like what you are looking for. I don't have internet access right now, but you can find the info in the OpenSocial spec (www.opensocial.org). Look for OpenSocial data.
Director, Platform & Ecosystem, Jive Software
President, OpenSocial Foundation