Facebook is a copycat (Friendster, MySpace, Orkut etc.)

Yelp is a copycat (CitySearch etc.).

Groupon probably isn't the first deal site.

If we didn't have VisiCalc and 1-2-3 and Excel, we wouldn't have Apple's Keynote.

That's how this industry works: large enough markets attract multiple companies. Increased competition causes all players to step up their game and lower their prices. This benefits consumer i.e. you and me.

This is exactly how things are supposed to work.