Goldeneye is a browser extension for Google Chrome that makes it easy to look up 4-letter alpha codes (aka "banding codes") as decided by the Institute of Bird Populations (IBP). It can be downloaded for free at the Google Web Store.
The extension currently supports full species name searches, as well as 4-letter code searches.
Actual app files are contained in package/. Other files contain the .CSV files of IBP and BBL alpha codes, plus the R program used to create a JS dictionary for these codes.