It is called a trackstand. You can do it on a geared bike too.

I trackstand, actually I prefer to sit, as I run clips and straps around town and I like to run them tight so it is a pain to reach down and unstrap and then tighten my straps again so I prefer to do a trackstand instead.

If you run across people who are good at trackstands movement is almost impereceptible, but those riders are seen less as FG riding is very popular and there are a lot of people who have not mastered some of the FG skills.

Try it on your geared bike sometime, easiest to do on a slight incline, and you might gain a better appreciation for it.