good point. But the core philosophy of both of them are very different. EventBrite is for organizing big events.. if you are looking for a buddy to play video game or if you are running a garage sale, its not the platform. Meetup is pretty close though - the core philosophy is you want to plan ahead and find people of similar interests. you need to have a continuous meeting groups. Its a big overhead and not a simple taks to lets say conduct a garage sale.

I would say tellStreet is more like twitter whereas, others are more like email groups.