Have you ever gone to some of the blogs hosted at Blogger and TypePad only to find out that you couldn't get the feed' I have and here is some of the info that I found:
- Typepad: add index.rdf to the feed url (learn more with some humour at Funny Business)
- Blogger: add atom.xml to the feed url (more info at CogDogBlog)
I'll add more as I find 'em.