I have tried to set up a mining pool with my home computers. I am running bitcoind on one machine, and the others, also running bitcoind, were started with --url and --userpass to my central bitcoind server.
Now, are these machines already forming a mining pool? Or am I missing something?
What other software should considered for a home mining pool?
You can create a private mining pool with just bitcoind. All mining software will work with it: just point the mining software at bitcoind's RPC port and use the appropriate RPC username/password.
bitcoind doesn't know how to do payouts or multi-user authentication, though, so public mining pools require additional software.
From what I understand, you only need one bitcoind instance on one machine, while other ones would only run miners that would connect to the bitcoind machine. Running more bitcoind than that is not necessary.
As for the software, you should look into P2Pool - it allows you to earn smaller amount of Bitcoins more often, meaning you'll get smaller variance. It won't decrease the amount of Bitcoins you earn on average though, meaning it doesn't cost you anything to use.
Eligius offers SMPPS (low variance, predictable income) decentralized and centralized mining, but more relevant to your question, our mining pool software, Eloipool, is completely free and open source. It does require a Linux server, however, unless you have the Python skills to port it to Windows (the main issue is epoll).
