So I've been thinking about this for some time. I'm not sure if anyone else has brought this up, but I think it would be a neat feature. You know how your not always online, but say your a designer or builder and someone needs to contact you, instead of waiting to check your mail or loggin in, what if they was a stand-alone messenger? That way when you don't feel like being in Second Life, or working on something else, people can contact you from Second Life via a messenger, or you can contact them.
Please give feedback, maybe this could become a reality.