Mostly out of boredom, I have created a spreadsheet which can be used to calculate a performance rating for any Warlight player. In short, what it does is compare your actual winning percentage for each type of game to your expected winning percentage. (For example, you would be expected to win 50% of your 1v1 games, on average. Doing better than this will increase your rating, and vice versa).
A more detailed description of the method can be found in the UserVoice suggestion I made a while back for this rating method: http://warlight.uservoice.com/forums/77051-warlight-features/suggestions/1166107-simple-player-rating-system
Long story short: A rating above 1.0 means that you win more games than the average player would be expected to, and vice versa.
Here's how to use the spreadsheet:
1. Visit the Warlight profile for the player whose rating you want to check (in a game, click their name, then choose "View Full Profile")
2. Scroll own to the "Ranked Games" portion of the profile. Copy to clipboard the entire set of game results, starting BELOW the "Completed XX ranked games..." line. For most people, the first line will be "2 player FFA: ..."
3. Visit the spreadsheet on Google Docs: https://spreadsheets.google.com/pub?key=0AtX-tYU73JXCdGV2bFY0c3pNN21FNlptYmx5dlB2dUE&hl=en&output=html
4. Select "Edit this page" and sign in (you will need a Google account)
5. Make sure you are on the "Data" sheet (sheet tabs are at the bottom of the spreadsheet)
6. In the top left cell (A1), Paste the game results which you copied from the player profile. You may need to try multiple methods of pasting to get it to work properly (for some reason, it doesn't work for me if I right click and choose Paste, but pressing Ctrl+V works fine). Column A should now be filled with the game results.
7. Switch to the "Calculations and Results" spreadsheet to view the results.
You will be most interested in the last two columns, which are both labelled "Rating." The first rating column provides a performance rating for each game type (1v1, 3 player FFA, etc.), and the last column provides a single rating for all game types combined.
Known issues: Currently, games with uneven members on teams are not properly supported. I'm not sure there is a good way to calculate an expected winning percentage for a 4v3 team game, for example. For now, the spreadsheet just assumes that all teams have an even number of players -- in the future, I may make it ignore all uneven team games.
Hopefully some of you enjoy this! I think it's quite fun, and a nice way to get a quick idea of how strong a certain player is.