Combining multiple atom feeds into one

I have 4 resources and I'd like to provide an atom feed for each one but I don't want to ask people sign开发者_StackOverflow社区 up for 4 feeds (cos they won't) so is there a guide that explains the best way to combine multiple atom feeds into one master feed?

Answering my own question here. So far I've found yahoo pipes and rss mix that can do this job.