I listened to Talis' Library 2.0 Gang on the OPAC (Online Public Access Catalog, or the online version of the old card catalog) this morning. They raised some interesting points. I recommend a listen for you librarians out there.
They eventually got around to talking about Open WorldCat. Open WorldCat is cool because it tells you which libraries have the item, but I think libraries need to make a more concerted effort to ensure that their holdings are in it. It also has a link to purchase the item for those who would rather buy or don't have a library near them that has the item. I'm pretty sure that used to link out to Amazon, which is a nice tie-in to a well-known site, but instead now it gives you the option to buy the book from OCLC.
Okay, so after further investigation, I see that sometimes it links to Amazon - apparently when OCLC does not have a copy of the item for sale.
Here's an interesting feature I did not notice before: When I click on the OCLC option to buy, it tells me: "Your purchase supports Muskingum College Library." I'm not sure I like that because it's definitely misleading. It certainly doesn't support my library directly (at least not that I know of, but hey, if OCLC wants to start sending us a percentage of the money they make off our users, that's fine by me!). Apparently you can even "Choose a library to support" if it doesn't automatically recognize you as a user of a certain library! Anyone know anything more about this? I'd do some Internet hunting, but I'm feeling decidedly unlibrarian at the moment. :)