Is that the WorldCat in your pocket, or are you just happy to see me?

WorldCat is our union catalogue of about 56 million bibliographic records, which represent approximately a billion holdings. It is about 50 gigabytes in MARC Communications (100+ gigabytes in XML) format and about 23 gigabytes compressed. Thom has a 40 gig iPod which can accommodate WorldCat on its disk with room left for 5,000 song tracks.