Can anything be done with the succubus hair from durlags tower or is it as useful as wet toilet paper? LOL

Give the hair to Riggilo, the thief lurking on the same floor. He'll be suspicious and you respond to the effect that you 'don't want a dagger in my back'. He will then give you a strength potion in exchange for the lock of hair. Then return to Kirinhale and she will give you a reward. Further conversation with Riggilo makes him hostile.

Oh no, a hostile Riggilo. (cowers in fear)

I should add that giving Kirinhale's hair to someone is Evil, in case anyone failed to make the connection while talking to her. She does have a nice butt, though.

The first time through Durlag's I held on to it and took it to Sorcerous Sundries hoping that I might get a cloak spun out of it, as with the nymph's hair in the Razimuth quest.