Honda has teamed up with Kelley Blue Book to offer car owners a way to estimate the trade-in value of their vehicles. A link on Honda's Web site will take visitors to a form where they can fill in the make, model, specifications and condition of their automobiles. Using information from a database on its own Web site, Kelley will use the data to calculate a trade-in value. Kelley offers a similar service on its site. Kelley and Honda did not provide details on the length or financial terms of their partnership.