There are plans to bundle an original anime DVD (OAD) for upcoming volumes of both the xxxHOLiC and Tsubasa: Reservoir Chronicle manga series…

On January 16th, 2009, the limited edition first-press release of xxxHOLiC volume 14 will be accompanied by an OAD.

On February 2009, volume 26 of the Tsubasa: Reservoir Chronicle manga series will be accompanied by an OAD.

Each OAD special is expected to run for 25-minutes; produced by Production I.G.

[Source]