Although most of the focus right now is on which players the Detroit Lions will re-sign and who could be targeted during free agency, it's important to remember that they can also make trades. Two years ago, the Lions really improved their roster through trades, leading to the term "Mayhewing" being coined by fans.
One of the trades Martin Mayhew made in 2010 was to get cornerback Alphonso Smith from the Denver Broncos. In addition to exchanging late-round draft picks, the Lions sent tight end Dan Gronkowski to the Broncos in order to acquire Smith, who had a pretty good season until he had a rough game against the New England Patriots on Thanksgiving and later dealt with injury issues. This past season, Smith appeared in 11 games and had three interceptions, one of which was returned for a touchdown.
According to NFL Network's Jason La Canfora, the Lions may be looking to move Smith this offseason and have actually actively "shopped him to at least one team."
Lions willing to move CB Alphonso Smith. Have shopped him to at least one team. Was a 2nd round pick by Denver in 2009 #insideslant— Jason La Canfora (@JasonLaCanfora) February 25, 2012
It's not clear what the Lions are looking for in return for Smith, but I would imagine they are after a draft pick in one of the later rounds. Due to the tampering charges, the Lions are without a sixth-round pick, so perhaps dealing Smith could help them make up for that fact.