Well, the shear tabs you mentioned are one. Flip-flop is another. Cogs for the disc set up are only available from Boone (in Titantium). You could drill yourself, but you better be good. Front hubs are made for a smaller spacing meaning more axle will be hangin off each end, more chance to bend. Chainline: the Level can be adjusted by flipping the assymetrical cog. Those are the ones I can think of.

I know people who are running the Boone cog on a rear disc hub. Not sure if the front disc hub will produce the same chainline. And I'm not sure what the chainline is for the rear, so you might need to play with things up front (chainrings).