Worldwide we have many ranking mechanism for brand, the more popularly accepted ones include
Interbrand Best Global Brands Survey , which would include a detailed report on how the ranking is done,
BrandZ Ranking 2008, is also a good resource
But in India we still don't have a well accepted raking which we can follow, only one which has been doing this on a regular basis is the Brand Equity Most Trusted Brand Ranking , link
and this survey has a fair bit of industry acceptance too.....