The European Library created an access widget that you can place on your website or blog. When visitors on your webpage enter a keyword they can quickly check whether one of the national libraries in Europe has a particular item like a book, movie or anything else. .
The widget is free. All you have to do is have the access code of your website ready and
provide your e-mail address and the URL of your site. " If you don’t have a code, request one by mailing the URL of your site to firstname.lastname@example.org"
When all the required information is filled in, a generator will create a code that you have to copy and paste on your webpage.
To promote themselves many libraries have adopted toolbars. I think that a widget like the one above is even better way to meet your library users where they are and connect them with the catalog.