Heres a cool product I found on a German fly shop web site. These are not for the dry fly guys and some folks may cringe, but these seem to be a neat product nonetheless.
Heres a description from the website:
Unique, pre-formed body nymph from a combination of plastic and tungsten.
A great product, complete with brains, a strong chest and a segmented body.Can be easily integrated with three-thread or with a thin Dubbingstrang on the hook shank.The high dead weight, the use of lead wire or beads unnecessary.This body can be colored with waterproof markers or colored lacquer.Available in 8 sizes.