As you know, this sport is fun for many reasons. As sad as it is to break something, I think that is half the fun to disassemble the revo, know how everything works, and get the satisfaction to know you fixed it. Also, I think this would be good for us newer guys to get a good idea of what tends to break the most to have extras on hand! I've already learned of the common breakage points and have extra parts. Also, if I am buying a spare part and its cheap - I'll usually buy two of them so I can have another on hand.
Rear push rod
Front right & left bottom A-arm (never the top, just the bottom).
Rear axle carrier
EZ Start Wiring TWICE! (where it connects to the ez start motor)
glow plug wire (after repeated removing and installing new glow plugs and the wire)
Reverse servo linkage (not sure how this happened)
Reverse servo (as I was screwing on the linkage I broke)
All dust boots (old age)
Cooling head cover
Cooling head fins (ran w/o the plastic engine handle/cover. Bad idea)
Wheels ripping from rim
Pretty much every skid plate under the revo
original revo body
I bash, and I bash hard. Its a lot of rock climbing, mountain climbing, and lose rock/dirt with steep drop off kind of driving. I'm a lot more careful now and have more skill so I haven't broke much lately /