The prior mentioned WorldCat has just gone public. This means that now you can search all participating libraries catalogs. This is useful is several regards. First you can find research articles and digital items and retrieve them this way, even if your own library doesn’t have them. Second, if you need a book that you library doesn’t have WorldCat lets you put in your zipcode and will show you all the nearby libraries that have that item. If you are in a pinch, don’t want to wait for ILL, or live in an area with lots of libraries this is tremendously useful. You could also use it to contact your friends at other universities with access to the book to track down that reference you can’t get at your library. All you need is a web browser.