1. Pylon Racing
Chuck, a local friend, is a big fan of this one. In fact, we are about to reintroduce a pylon racing contest at a local club after a hiatus of several years. I watched a pylon race many years ago. You really have to pay attention to keep up with it. These airplanes move fast! In those days the pilot stood inside a metal cage near the pylons. Nowadays the system that they use is much safer. Everybody stands well clear of the flying airplanes.
2. Lighter Than Air
I hardly hear anything about this one, but the impression that I get is that there are small pockets of fans throughout the world. I once went to a pro basketball game, and during the breaks, I was very surprised to see a local flying buddy come out with a large RC electric blimp to entertain the crowd. Turns out he had been a fan of lighter than air RC models for many years. I have seen large helium-filled fish that swim around like real fish. Looks like fun, and very relaxing.
3. RC Combat
I keep dropping hints around town that I would love to watch some RC combat. So far, no takers. I attended a contest once, and it looked like a lot of fun. Crashes are common, so safety is important and disposable airplanes even more so. It is very hard to do! The airplanes were just a blur as they flew around trying to cut the other airplane's paper streamer.
4. Old Timers
These are the domain of the Society of Antique Modelers (SAM). They claim that the antiques are the models, not the pilots, but sometimes I wonder... These are some gorgeous models, partly because the folks that put them together are usually the most experienced builders around.
5. Fun Fly Competition
I was a judge at a fun fly competition a couple of years back. Most were indeed competing just for the fun of it, but all the top finishers were very serious about it. One participant even had a custom-built airplane just for fun fly competitions.
6. Control Line
I flew control line a lot while growing up. I was living in Queens, New York at the time. A local park had a couple of circles set aside and they were pretty popular. Those were my "Cox.049 days", since that is mostly what I flew. Very inexpensive, and relatively safe. It is not as popular as it used to be, but there does not appear to be a shortage of guys that still fly them around here.