First, I'll add to the fun wrecks I've seen/had while stunting.
1) My all time favorite, the stall. While doing a highchair, or spreader, or trying to do a real slow wheelie. You either hit the kill switch and shut the bike off, or go too slow and stall it out. The result is a mouse-trap like action that slams the front end into the ground and sends you sailing over the clipons.
2) The "endo". Often caused by too much brake pressure or throwing too much weight forward when attempting a stoppie. Pretty simple explination. Rear comes up... and keeps comming up. You get catapulted off and if your luck is running thin the bike lands in the middle of your back. Good times for sure!
3) the ape hanger sucker punch. While doing an ape hanger (the bike is dragging along the ground on the 12 bar, and you hold onto the clipons and drag your feet behind the bike) the bike stalls out and goes slamming forward (just like number 1) since you aren't on the bike, it comes back onto both wheels pulling you up nice and quickly into the big sharp 12 bar crushing your ribs like a sucker punch.
These are just a few of the fun things that have happened to me in my travels.
As far as the other that Vash posted...
The tank slapper. I have a couple clips on here and from other videos that I own that show some killer slaps. tossin people like rag dolls. You've just been lucky so far...
The sideways fall. Usually the sideways fall is just from a rediculous amount of weight transfer. It happens a lot on two up stunts, and with slow stuff where there isn't a lot of gyroscopic (sp) effect on the bike. It just kinda falls to wherever the most weight is. Happens a lot with circle wheelies and other slow stunts.
as far as the potholes go. Just wait until you get into a groove in the road while wheelieing. It sucks you in like a tractor beam and won't let you out. the wheel just stays in the groove and often causes the wheel wobble thing you were talkin about. To compensate for this, lower your rear tire pressure when you know you'll be stunting. it makes it less likely to wobble and has more surface area. Helps a lot.
I'm sure I'll post more when I get bored. Feel free to comment and ask questions!
~ the super