Tablenator από Charah.ca

Tablenator assists developers in making tables accessible. The add-on eliminates everything from a web page except for the tables. The add-on numbers the tables, and shows any issues it finds with the tables. For example, it indicates tables where there have no accessibility markup, or tables where there are conflicting accessibility markups.

The add-on also indicates, with colour, the relationships of tables cells with other cells.

Details about this extension can be found at http://tablenator.com