Xobni for Outlook
I've been having a look at Xobni since Viral told us about it a few weeks ago and I'm impressed. I hadn't really thought about it as a social networking tool through email until I saw Bill talking about it.
The thing I like best is the Stay in Touch feature:
Or more like the guilt tasks feature :-)
Want to schedule some time with one of your contacts? Xobni looks at your calendar for your free times and pre populates a mail to the contact.
Hi Andrew,
Here is my availability for the next few days. (All times are GMT Standard Time, GMT+00:00.)
Fri 14 March, 09:00 to 14:30, 16:30 to 19:00
Sat 15 March, 09:00 to 13:30, 14:00 +
Sun 16 March, 09:00 to 12:00, 14:00 +

You can see who sends mails at certain times of the day. Here's when James tends to mail me...
There are many more features than this - but don't take my word for it - go on - get yourself an invitation to the trial and find out for yourself...