For the 2010-11 season, Matt Bonner of the San Antonio Spurs would be paid an additional $100,000 if the combined total of his three-point shooting percentage, free throw shooting percentage, and field-goal shooting percentage added up to 169. He combined for 157 percent shooting during the 2010 season, so he ended up with no extra money.
Nick Collison would be given an extra $100,000 if he were to win an MVP award.
Due to weight concerns, the Heat used to give Mario Chalmers $19,580 just for showing up for summer league, and for going through a team "skill/conditioning program."
In 2009, Clippers' Baron Davis was contractually obligated to receive an extra $1 million if he played in 70 games that season and the team won 30 of them. At the end of the 2009-10 season, Davis had played in 75 games, leading the Clippers to a 29-53 record…one win short of a million-dollar payout.
Michael Jordan's "Love-of-the-Game Clause". MJ could play in exhibition games, scrimmages or just a pickup game in a random park whenever he wanted—the only player that general manager Jerry Krause ever thought about giving this clause to.
Adonal Foyle would be given an extra $500,000 if he were to win MVP, and another $500,000 if he were to win MVP of the NBA Finals.
In 2009 Tony Battie, then on the Nets, had a base salary of $6 million, but he was owed an extra $100,000 if he played in 50 games and averaged eight rebounds, another $100,000 if he averaged five free-throw attempts in those games, and an extra $100,000 if he was active for 50 games and his team made the playoffs. Battie played in just 15 games in the 2009-10 season, so he ended up getting none of that extra dough.
Glen Davis' contract when he was with the Celtics included he would be given an extra $500,000 if he were to make an unspecified weight at certain points in the season.
Larry Hughes was guaranteed a $1.6 million bonus if his team -- whatever team he was going to be on in '09-10 season -- won 55 games or more.
In 2006 Luke Ridnour signed a contract with Seattle SuperSonics, with a clause he would receive an extra $1.5 million from for winning Defensive Player of the Year award.
Devean George had a no trade clause in his contract he received from the Mavs in 2006, this caused problems when he was included in the trade for Jason Kidd. This then resulted in one of the strangest contracts ever where Keith Van Horn was paid about 4 million dollars to do nothing but show up so the trade could go through financsially. Van Horn hadn't retired, but wasn't signed after his last contract in 2006 so therefore the Mavs had his Bird rights and could sign him to this absurd contract and complete the trade.
Pretty sure Boris Diaw has a weight related bonus in his contract as well.
But the cheekiest I ever heard about was in Bill Simmons' nook of basketball. The details are vague but I think it was Spencer Haywood who was given a big contract but didn't notice that it was to be paid over a 20 year period so he was getting screwed.