For those uber-geeks out there, here's a good Linux network tuning guide for those of us running high performance network applications. I suspect that just about any server would be improved with many of these settings with little penalty aside from system memory. Here's another good page from Jboss.

Another thing you can try that may help increase TCP throughput is to increase the size of the interface queue. To do this, do the following: ifconfig eth0 txqueuelen 1000

I've seen increases in bandwidth of up to 8x by doing this on some long, fast paths. This is only a good idea for Gigabit Ethernet connected hosts, and may have other side effects such as uneven sharing between multiple streams. Also, I've been told that for some network paths, using the Linux 'tc' (traffic control) system to pace traffic out of the host can help improve total throughput.