Bending axles

Does anyone have any suggestions on good quality rear axles?
I keep on bending mine. - I don't jump curbs, and try to avoid pot-holes etc., but I am a bit heavy on the throttle.

had a customer doing that - he was hard on the clutch and he often adjusted chain too tight at its tight spot - he was also breaking spokes on the rag joint side and not noticing because they were held by the rubbers

What sort of hub and axle do you have?

Sean:
It's a solid rear axle (no quick-release), and an aluminum hub (I don't see a brand name on it).
I'm also running a Sick Bikes jackshaft kit with a 7 speed cassette.

Are you sure it is a cassette? Cassettes and freewheels are different (see link). I ask because a freewheel is more prone to bending that a cassette due to the drive side bearing being farther inside the hub. Either way I would look for Titanium or Chromoly axles. If you post the length, diameter and thread pitch it would be easier to help find a replacement. I'd check around google/ebay/amazon or many give a call to you Local Bike Shop.

cassette VS freewheel
http://www.sheldonbrown.com/free-k7.html

Sean:
Live and learn! It's a freewheel, not a cassette. I had never really paid much attention to the difference, and the reason for the desirability of the cassette, especially when you're applying engine power to the axle through the gearset. Also, when I think about it, for a while I was having a problem with the engine refusing to go back to idle, causing chain snatch when shifting. I'm sure that didn't help. The drive side bearing being farther inside the hub would make a big difference.
Sadly, I just replaced my rear wheel assembly, but next time for sure it will be one with a cassette style hub.
Thanks a lot for your help. - I really appreciate it.