Went to the Groton House Farm Horse Trials to watch the cross country event. It was pretty awesome, cross country is a timed point to point event across a mix of forest and fields with a set of jumps interspersed all along the course. Since its all over hill and dale as a spectator you can only really take in a small segment, similar to a Rally race, but they cycle through riders fast enough that there isn't much of a break in the action. My novice skill level in horsemanship isn't anywhere near what it would be to try something like this but it's certainly something to aspire to, it looks like damn good fun.
Though I noticed while looking through the event program that out of 300 plus riders probably less than ten are men. Considering that riding is a such physically and mentally demanding sport, I am surprised it doesn't seem to be that popular with men. Not that I'm complaining that it's mostly made up of cute athletic females.