Like I said there is scant evidence that they ever made much use of it (but its impossible to prove it either way). Mountains of it was found after the war in the camps, and I believe more of it was burned. There is the reference to using it in socks for u-boat and railway crews, but no evidence for production of such items, though there are a few surviving shipping records of smaller amounts of hair being shipped to certain furrier firms.
This letter
http://www.nizkor.org/hweb/camps/dac...e-of-hair.html was sent to all the commandants of the major concentration and death camps, ordering that human hair from their victims be saved to be shipped for future industrial use. I searched around for any other documented evidence of use but couldn't find much of value.
Anyhow here are some links.
Human Soap
http://www.nizkor.org/ftp.cgi/camps/...c_confirmation
Archeological Investigations of Belzec (for any holocaust deniers here), one of the death camps. It is estimated to have killed over 800,000 people.
http://www.jewishgen.org/yizkor/belzec1/bel150.html
http://www.holocaustresearchproject....rchreview.html