Increasingly called "special editions" or "event-only" rather than limited editions, from the late nineties through about 2007 was probably the heyday of Citadel limited editions.
Pieces were produced to commemorate specific events, such as Games Day, or major milestones in the company's history. Several promotional editions were created for use by different GW Organizations. Some pieces were also created for Staff recognition.
Special Edition pieces were produced to promote the army and game boxes from Christmas 1999 until 2007. The Skulz sales promotion was run in several countries to promote sales. Customers could collect stickers that could be sent in for a variety of items.
A number of limited release pieces were also issued in conjunction with the partwork Battle Games in Middle Earth.