Good starter tricks for urban mountain biking?

I've been mountain/trail biking for a while now on my hardtail diamondback response, its fun but I want to try urban mountain biking, the stuff they can do is simply amazing. What are some good starter tricks to help get me in the sport? I know how to wheelie, but can only hold it for like 50ft. and a basic front brake stoppie, but thats it. ANy help or reference sights to recommend would be great.