On the Knot Heads World Wide site, member ShamrOck has been using Jimalax Crosslace cord for some knotting projects for a while now, with great results. So I thought I'd give it a try. The cord is made for use as net material for the stick, in the sport of lacrosse.
I ordered a 100yd spool in black, from ComLax. So far I've just made a few things with it, and I really like the cord. It's about 2.5mm in diameter with a tightly braided outer sheath over 5 inner strands, with a stiff feel to it, like some bootlaces I've had in the past. It's available in a variety of colors. Another site that also sells the cord is Jimalax.com.
It's not 550 paracord, but I think it's still a good alternative for knot work.