SharpRangeCollector

Just install the addon to your beta client, and play the game. The more varied the gameplay (leveling, world quests, dungeons, raids, arena/bgs, etc.) the better, but anything will do. Turning on nameplates (enemy/friendly) helps collect more data too.

To send over the data, send the file:

[WoW Directory]\WTF\Account\[Account Name]\SavedVariables\SharpRangeCollector.lua

(Note: This is not a game-enhancing addon, nor an API or library. Rather it is a data collector similar to Wowhead Looter or WowDB Profiler. The data is intended to be used in an upcoming range checking addon.)