We tried to make a new hammock a few years ago. After much finagling, we were successful, but Martha (oh that Martha...) has gone and made it so simple!
Check out how she's taken a basic dropcloth and used it as a ready-made hammock. Ingenious really—thick, durable, weatherable fabric, ready to be grommeted and hung. See her step-by-step instructions here.
With all this snow, I'm so ready for hammock weather!