Kite surfing is one of those sports that looks so awesome and appears to be so much fun, but can in fact be deceptively dangerous - especially for the foolishly brave noobies who think that it's okay to go out on their own. It really isn't okay for the inexperienced to kite-surf on their own, even if the wind is calm.
The Cape Town wind has a nasty way of arriving suddenly and changing unpredictably. A friend of mine was once lifted several metres into the air, and then thumped down on the sand, severely injuring his back. It took months for the feeling in his lower back to return... and he was lucky. More than once have I heard of kite surfers being dragged around on the beach, slammed into barricades and even dragged across roads. A little while ago I heard a report of a kite surfer flying across the beach, then flying across the road, and finally being slammed against a building.
If you do plan on taking up kite surfing, make sure that you take proper lessons and get in a good few hours of surfing before going out alone. Also, take a look at the safety tips on this kite-surfing school's site. And, just before you're ready to go out and buy your first kite, do take a look at this video. (Warning: The video contains no blood, or visible damage to any person, but could be classed as horrific in nature.)