Worldcat.org is such a practical database for
Inter Library Loan checks and other big picture book, DVDs,
CDs and periodical searches. There is a great review via
Resource Shelf to the Charleston Advisor. The full text of the article is available in article form in
Eprints. The Jeffrey
Beall review covers such things as the periodical
component of the database covering ~20 million articles. There is also other interesting tidbits in the review and it is worth looking at even as a refresher on what is in the database.