I thought that we should have a thread on running a Tor relay from home, as it didn't seem to fit in with the existing Tor thread. There are several benefits, namely that it mixes any traffic you yourself make on Tor with the traffic of others, which could make it harder to perform traffic correlation. It also increases the bandwidth of the Tor network, of course.

torrc Relay Configuration
Nickname <your nickname>
ORPort 9001
ExitRelay 0
SocksPort 0
ControlSocket 0
ContactInfo <your email>

This config sets up the Tor daemon to run as a middle node. I'd recommend using a separate email as the contact info. The nickname can be anything you want.
It's possible to run it as an exit node, by changing ExitRelay to 1. However, this is very likely to bring the attention of your ISP/Law Enforcement, and you'll probably get banned from many clearnet sites.

It's best to check if your ISP cares about running a relay; mine is apparently fine with it, but I imagine that some may get annoyed and send you letters, or rate limit you or something like that. There's a list at https://trac.torproject.org/projects/tor/wiki/doc/GoodBadISPs, although it is incomplete.

This thread would probably be good for discussing running similar things with other networks (BT seedboxes, GNUnet nodes etc).