Does anyone know what the heck this is?   Found it the other day.T
The grey part on the right slides and is spring loaded

knot tying tool...nail knots and such

That's what I figured, I see the nail knot part.   The spring loaded end has me stumped though it pulls away from the metal end.

vise?

The end is solid

This thing is cool I found a video on E bay
http://www.ebay.com/itm/T...mp;hash=item2323d31721

I had one years ago but can't say where it is amongst all my fishing stuff.  I think I bought mine at the outdoor show at Rockland Community College.  Its a knot tying tool that ties the fastest improved clinch. 
The newer model that's in the 3 in 1 video does much more than the original which has been around since the early 80's if not before.