The Hotlist
http://www.thehotlist.com/

The Hotlist is the world’s first geo-social aggregator that shows you what’s going on today, tomorrow and throughout the week among your personal network of friends. A custom “hotlist” is generated for you on the places and events your friends are planning to attend and when they’ll be there – so you can easily make plans and connect in person. This has been added to the tools section of Research Resources Subject Tracer™ Information Blog.