As you know, Magic uses the Elo system for its DCI ratings. You might not be aware that it's named after its creator, Arpad Elö, who invented it for chess. That's not all that relevant, but we thought we'd throw you some free information. You're welcome! Incidentally, that means it's just "Elo", not "ELO". ELO is Jeff Lynne's old band, which did a number of songs on the soundtrack to Xanadu. It's possible that we're getting off track from today's topic, which is the complex formula that calculates ratings.
From time to time, people propose changes to the system. Many years ago, the DCI went with "Variable-K", allowing bigger tournaments to have bigger effects on ratings. For some background on the Elo system as it applies to Magic, Jeff Till's Getting To Know Your DCI Rating on Star City Games covers the basics.
The most recent player-led proposals on changes (or replacements) for the Elo Ratings System appeared on TheStarkingtonPost.com.