If you need a lot of storage capacity in a flash drive, but also need the ability to encrypt the contents of the drive to keep sensitive data safe Kingston’s 4GB Data Traveler Secure can do the job.

This drive uses 256-bit AES hardware encryption and wraps the drive in a durable case to keep it safe during daily use. The Kingston drive is a bit larger than the other flash drives on the market, but for the added piece of mind encryption brings and the large 4GB storage capacity I think most of us can overlook the portly design.
Everything USB Review excerpt: Overall I'm quite impressed with Kingston's Data Traveler Secure. It's highly durable outside of being crushed by an SUV, doesn't require drying for hours after an accidental couple of minutes in the pool, it's speedy, self-destructs, and doesn't suffer any performance hits when encrypting files." Buy your own Kingston flash drive here.