The preview for Lifehacker returned nothing at all, but adding the feed to Google Reader worked as advertised. I guess, don't rely on the preview box.

This may be common knowledge, but all gawker blogs are available in full feed, ad free form at <gawker entity>.com/vip.xml

i.e. http://lifehacker.com/vip.xml

Ah, I see I'm not the first to point this out :)

Funny, I just added sfgate too and it worked for me: fulltextrssfeed.com/www.sfgate.com/rss/feeds/news.xml

Hrm, that one loads fine... but fulltextrssfeed.com/www.sfgate.com/rss/feeds/blogs/sfgate/offtherecord/index_rss2.xml fails with "unable to retrieve full-text content" and fulltextrssfeed.com/www.kqed.org/rss/arts.xml fails with "Unable to parse this page for content."

I have a lot of experience with fetching and parsing feeds and pages, so I'm not trivializing the problem, just observing issues I'm seeing with this solution.

works for me. did you test out the default CNN feed? does that work?