trackstands of all forms, one foot on the front wheel included, date back to the early days of the bicycle. BMX didn't invent much on flat ground tricks, but it did redefine the trick bicycle. Look into indoor cycling (hallenrad), specifically artistic cycling. that stuffs been around for like 100 years. they do stuff that makes free style BMX look weak. On the other hand, nobody has anything on BMX vertical tricks and grinds and stuff.

McBomb, if you really think BMX hasn't invented much on "flat ground tricks" I'd say you probably want to get up to speed on flatland post, say, 1989. Here's one sample.