Andrew,

Jumping on the bandwagon, I have to agree, spinning flies make a mess of the tippet and leader and possibly even the line.

Norm Norlander, in his DVD demonstrating his Nor-Vise, mentions that flies like Woolly Buggers can have a tendency to spin so he starts his hackle at the front of the fly, palmers it back to the rear then back up to the front again. He says this makes it so the hackle will not spin your fly. I have started doing all my hackles this way on the sub-surface flies.

Here is a link to his You Tube site where he is talking about the hackle:
http://www.youtube.com/watch?v=X13Ff73vSB0&feature=related

There are some streamers that wreck havoc on my leaders and lines when I am casting for smallmouth bass or out in the saltwater for pinks or Searun Cutthroats. I have been tempted to tie in a very small barrel swivel between the leader and the line. I have yet to do the swivel but I suspect it would take care of the tangles.

Larry ---sagefisher---