You can usually limit upload speed with a setting in your router. It depends on your router's firmware. I know that DD-WRT can do it. I suspect that various stock firmware also has that ability. It might under something called QOS (Quality of Service). Personally, I use the Traffic Shaping feature of IPCOP. I limit my upload speed to 500 kbps (a bit over 60KB per second), and I typically have 50-60 peers. They have to share the 60KB, so each is getting on average about 1KB per second.