They keep a database of teas indexed by brand, style, and region. Although it is not the largest database on the web (Steepster currently has a larger database), the site claims to be the most detailed database available. Single-region teas are classified to the level of provinces, states, districts, or counties, when this information is available. Rather than classify teas broadly (black, green, etc.) they identify particular varieties of each of these broad classes of tea, both to help people discover the vast richness of tea traditions, and also so that teas can be compared against truly similar teas.
Check them out at RateTea.com