Hi there,
I can thoroughly recommend FreeBMD as being a great experience for a volunteer transcriber.

I am with the Freeloaders syndicate, all is done via Email and internet links. There are about 100 in my syndicate, all over the world and our co-ordinator is in Australia. It is easy, all the software is very user friendly and downloadable over the 'net.
All you need to contribute is your time, and as much or as little as you can spare. There is no pressure on transcribers and all is friendly and a great feeling of cameraderie.
If you ever need any advice or help I would be happy to hear from you, and I would urge anyone thinking of contributing to this project to go ahead, give it a go. As family historians we all benefit from the results.
Kazza.