I'd love to use this for finding co-founders or team building, so some form of grouping feature would be helpful to organize certain overlaps together. After signing up and adding a number of overlaps I immediately thought that this is how Hunch, Quora, and/or LinkedIn should feel in terms of experience. So far I really like this. Looking forward to seeing it grow.
It's a great idea and I've experimented with UI's for grouping in the past (grouping/lists were a victim of the simplify-before-launch phase).
All tweets, blog posts, postcards, phone calls to friends, shouts from rooftops etc. would be greatly appreciated in helping Overlap grow ;-). My marketing budget is less than what I spend on coffee, and I'm currently in Colombia.