I just noticed a strange bug with Digg’s RSS feeds: when you subscribe to a feed for a search term (to monitor submissions of your blog posts, for example), sometimes the feed will be invalid because it is missing closing </channel> and </rss> tags. This means that the feed won’t be parsed by most readers, and you won’t get updates of any new items in the feed.
The weird part is that this doesn’t happen for all search terms. I found that the chris, efinke, and charles feeds are all malformed, but the feeds for apple, kevin, and rose are not. My best guess as to the cause is that some item in each of the malformed feeds is causing the code that generates the feed to die prematurely, leaving the feed incomplete. At any rate, I’ve reported the bug to Digg, and it will be interesting to see how long it takes to get fixed.