I'm a noob with under 1000 miles under my belt. I've crashed three times.
Once, right after I put knobbies on my mountain bike (used bike, came with slicks for commuting by the previous owner) I decided to putz around in the torn-up pre-construction stuff near my apartment. I went down a 6 foot drop at about 45 degrees, but did not see the giant boulder under the thick, tall grass. My wheel hit it and it tossed me off. I was on the brakes pretty good already and leaning far back to maintain balance, so I wasn't going fast. It broke the mount on my headlight, nothing more.
Another time, I was on my hybrid. I swapped the slicks from my mountain bike onto it (makes more sense than knobbies on a hybrid, slicks on an MTB). It was raining hard, and on my way to the bus stop, half the outer lane was full of silty, slick clay mud. It was almost orange and in the pre-sunrise light it looked like sand under a thin layer of water. It was too late to move to the inside lane to go around it, so I attempted to coast through it at about 25 miles per hour (just coming out of a downhill). I failed and slipped, sliding on my left side through the mud for about 50 feet or so. You should have seen the looks I got boarding the bus.
The last time was during our last snowstorm. The mountain bike is sure-footed in ice and snow, but not when I am trying to show off. Some people at the bus stop downtown were pointing at me coming down the road. The snow was powdery and coming down really good and I work with one of the people. I decided it would be fun to do a sideways skid and throw snow on them. I failed and slipped, sliding on my left side through the powdery snow for about 10 feet. Not the result I was looking for but damn was it fun.
Had my helmet on all times, but it wouldn't have mattered as I didn't hit my head any of them. No injuries so far, just hurt pride.