Updated for WotLK. Contains Pre-raid and T7 bis lists.
BiS-Tooltip - is an add-on providing in-game information about best in slot items.
It consists of two parts:
1. BiS list window - accessible via minimap button or /bistooltip chat command.
2. Item tooltip enrichment - shows item BiS list positions under item tooltip for various specializations/phases.
You can filter out some specializations that you are not interested in from the tooltip so that it doesn't look like a wall of text:
The data for this add-on is based on the BiS lists from the website: https://wowtbc.gg/