As elite quarterbacks and running backs are scarce and coveted in the NFL, so are the top cornerbacks.

Historically, many top cornerbacks have been acquired via a trade over the years, and with Darrelle Revis (the 2009 AFC Defensive Player of the Year and arguably the best cornerback in the game today) having been traded by the New York Jets to the Tampa Bay Buccaneers, it's worth remembering some of the other all-star cornerbacks who switched teams over the years.

In 1977, the first free agent in modern NFL history to switch teams (in a time when this practice was very rare, due to the very steep price the team willing to acquire the player had to pay: for players that earned more than $65,000 a year, the team had to relinquish their first and second-round draft choices) was a cornerback: Norm Thompson, who had played six years with the St. Louis Cardinals, went to the Baltimore Colts.

Since Thompson earned less than $65,000 even with the 35 percent salary raise the Colts gave him, Baltimore only had to give the Cardinals a third-round draft selection (for the record, Thompson went to play three more seasons with the Colts, without having been chosen to the Pro Bowl or to an All-Pro or All-AFC team).

With the start of unrestricted free agency in 1992, however, many top players switched teams each season. We'll look now at the top 10 cornerbacks (plus another three who also should be included) who changed teams, and continued their elite play in their new homes.