Some RSS feeds don't work in my wiki. I always use the same syntax, for all of them:
Some feeds don't have '.rss' or '.php', but I think that it don't matters. I didn't search dokuwiki's code to find the bug yet, but all RSS that I tested are recognized by Firefox and other feed readers.
The message is: "An error occured while fetching this feed: FEED-URL". I think that doku can generate more detailed output (with 'debug mode' on, the error is the same).
Sometimes a feed appear in page, sometimes an error occurs and it isn't showed. Some feeds (like ThinkGeek) never worked.
Some RSS that work:
Some RSS that DON'T work: