I rode trials for a few years before i discovered the biketrials side of it. It's a mixture of throttle, clutch and brake control, along with good balance and some balls! There's loads of clubs around and i can pretty much guarantee there will be an event on reasonably near you every weekend.
The bikes tend to be a fair bit cheaper to run than many other motorcycle sports too.
It's something i want to take up again in the future when money allows.
Always wear the right kit, (boots, helmet etc) and have fun!