You bet! You can sheath your iPod in the JitterBox 2600 PDA case ($50; jitterbox.com). It’s completely sealed with a patented waterproof membrane and the high-impact polycarbonate is waterproof, crushproof, and airtight and will likely come out of the spin cycle of a Class V rapid in better shape than you will.
The one downside is that this much protection adds a half-pound to your phone, which can be a drag on a fast and light outdoor adventure.
Have fun out there! ~Pan