Library Thing says it lets you create your own book catalog online (200 books free, or you can get a lifetime membership for $10 with unlimited catalog).

Sunday toast For who has some familiarity with the English, access to the InterNet and thinks about fichar its library. A small farm makes success that receives the heading from a book, searchs it in the Library of the Congress of the United States, captures its fiche and plays it in the archive of the customer. Librarything.com is called and was created by Tim Spalding, an American pc hacker with the feet in the classic culture. It is in the version Beta (with the risks that this means) and leaves favour for who wants to catalogue up to 200 books. For bigger libraries, it charges USS 10 for the limitless use of the instrument. In less of one month, librarything joined four a thousand users who ficharam 177 a thousand books. It gained news article in the "The Guardian" and the forecast of that somebody goes to gain money with this business. If it will not be Spalding, will be another person. The Library of the Congress is a colossus. Its catalogue has 28 book million in 470 languages. For example: 18 headings of Fernando Gabeira. (who to want to sapear, an acknowledgment: the instrument of not accepted search accents nor cedilhas.)
Catalog your books online : LibraryThing

Elsewhere: Bookrags: collection of online books, research materials online