Trading cards from different Olympics have some interest and value in the memorabilia and collectibles market. The greatest value is reserved for those individuals or teams which won gold medals, or that had particular historic and Olympic significance (the first Dream Team, for example). Beyond that, interest in these cards rest primarily with those who are followers of the event of the athlete depicted. As with all trading cards, condition is vital and the card should not be autographed.
Trading cards from less popular sports have limited value, are of interest only to those who follow that sport. Despite this, because interest does exist, it is important to keep the cards in tip-top condition, and not to have it signed. Research may be needed to find the market, but once done a good return should be realized.
A curious thing about professional wrestling, and WWE in particular, is that it is not permitted to present itself as a sport, but rather as entertainment. However, this does not prevent trading cards from being marketed in the sports category. The notoriety of the wrestler and the quality of the card are what determine its value. Wins and losses have little, if any, impact on value. Protect the card from damage and do get it autographed. Cards in mint or excellent condition of wrestlers from earlier periods are of great interest as well.
Tennis trading cards have a fluctuating value, depending on its popularity at the time in mainstream consciousness. When interest is at its greatest, cards are most valuable if they show the most famous athletes in the sport. The number of major tournament wins (those tournaments that are part of the Grand Slam) determines this. Card condition is important, so use protective sleeves to maintain mint or near mint quality. No autographs, please.
Soccer trading cards on the American market have limited appeal because of its relative lack of popularity. The greatest interest will be for cards in mint or near mint condition of high profile players from Europe or South America. Occasionally, and American player may become important enough to generate interest, but for the most part those icons from outside the U.S. are the most popular.
Motorsports trading cards have an audience of those who follow racing, and those who simply collect cards. The greats of the sport bring the highest interest, with other drivers or riders having limited value. Final determining factors are number of races won, the importance of the races, and the condition of the trading cards. Autographed cards do not have the same level of value or interest as those that are not signed.