The Onward March of the Bundles [See Post #1 for a full, up-to-date list]
The Onward March is getting an upgrade! To view the full list of active deals as well as the archived ones, join here!
All the deals are posted as threads inside the discussion system of the Steam Group, which makes managing and searching the thing a whole lot easier.
As an added benefit you can subscribe to boards (e.g. Active Deals - Main Sites) and get notified through Steam whenever a new bundle is live.
If you subscribe to individual bundle threads, you will get updates whenever keys get added, games unlock, and so on.
So don't forget to subscribe!