This is the supplementary link collection for the Guide to Web Design.
CSS 3 has been defined but currently it is only supported in parts by only a few browsers (guess, which one is not supporting any CSS3). Therefore the following links will be interesting only in the future.
Of course, including foreign code has it's disadvantages; You give away control and you don't know, what the script is doing to your web site. On the other hand, your page can be quite messed up, if they change things. It is best to download the scripts and host them on your own web space.