I highly, highly, highly reccomend Zing-it.
http://www.samsonrope.com/home/newarborist/zingitdetails2.cfm?ProdNum=70It's very light, and very slick. Strong, too. I use the 1.75mm size with an 8oz weight on it, though most people would reccomend the 10oz for that size line.
It is a bit more expensive that the other lines you can get, but so, so, so, so worth it.
For what it's worth, I have an eye spliced on my throwline. I just girth hitch the weight on to throw it!
love
nick