Hey there Betty,
An excellent example of link "Baiting" is this web page. It isn't selling anything. Instead, it is offering a list of free tools to help people edit photos and create videos, etc.
Another good example is This Page, which is simply a glossary of internet marketing terms. People may link to it, or bookmark it just for the convenience of the quick reference to helpful information.
Obviously, there are items on that site for sale, so the increased traffic will benefit the site. As far as helping out with Google PR, it all adds up.
A huge thing with Google is TIME! New sites take time to rank, unless there is an extraordinary viral mktg campaign that causes it to get tones of back links to the site over a short period of time.