I made something very similar. neartribe.com where you could video chat with people near you. Ran into similar problems as @sailorganymede where users would need to wait very long to be matched with someone & eventually get bored & log off.

The project is still live but in retrospect I would have started with a niche audience & let them decide on a time before hand. Then start on demand matching only when the site reached a critical mass of users.

On a side note I am impressed that your post reached the top page & got >150 upvotes. When I tried posting I was only able to get 3-5 upvotes :/