Beware cheap flash drives with crappy memory
As Trucrypt does literally mount and can be used easily (and there is TruCypt for MacOS too),
HOWEVER if the flash memory module isn't in the best of states, it can expose it to read/write errors either along the bus or within the unit itself.
That and there is one heck of a performance hit on R/W operations.
I'd suggest IronKey for a pretty much indestructible one, or Blockmasters "Safesticks". More expensive, but you get what you pay for IMO.
If you're in an environment that requires NO data to be written to a unencrypted flash drive, I would avoid the Kingston Flash Drives (due to the minor fact that they leave a portion of the drive accessible to anything even when you've encrypted as much of the drive as possible ).