Mathemagenic

RSS Neighborhood by Thomas Burg - I do not understand German, but I can follow the links. Check this out:

Similar Feeds uses Share Your OPML! data to produce Readers who subscribe to Mathemagenic also subscribe to...

The way to get it is not very obvious, so:

1. Go to http://grumet.net/syo/findThatFeed
2. Type the name of your weblog
3. Find your RSS feed (if there are several) and then click on <sim> next to it
4. Enjoy :)

Thanks go to Andrew Grumet :)

Update 1: Andrew says 

The query uses a fudge factor to filter out the most popular weblogs, which otherwise would show up every time.

You can play with including/excluding more popular weblogs by using Tweak results on the left of the list.

Example: weblogs more popular and less popular between subscribers of my RSS feed

Update 2: Try selecting a number (x) that follows every weblog title: it gives you a list of people reading both weblogs.

Example: people reading both Mathemagenic and Ton's Interdependent Thoughts

Do not forget: all these nice things are built based on RSS subscription lists in Share Your OPML!, so not everything is there ;)