This is an interesting one for me because when my husband and I had daughter no.2, extra child care just wasn't a financial option (those of you, like me, who have been stung by the Uks WFTC system will know what I mean!). At the time, I had a very well paid job in HR so I needed to return to work which meant that my husband was the one who stayed at home to look after the girls. He used his army training to start a domestic ironing service. We're now 18 months down the line and his business is still going and doing very well and he still runs it from home.
There are a couple of good sites to offer information if you want to work from home although I agree with Seb - don't' fall into the trap of these 'get rich quick' schemes, they are very rarely genuine opportunities. I wrote a blog post on this very thing a short while ago with some good links. (http://conceptcv.typepad.com/conceptcv/2007/09/britain---a-nat.html