You will be surprised to find that you can play almost any hero as support, it really depends on how you move within the game and the items you build. You can make heroes have a lot of AP for amazing damage, or conversely with lots of attack damage. Or you can make a hero have really low spell cooldowns as well as additional affects. There is nothing wrong with going support, but remember, if you're going to be a support hero you must make sure that your team can utilize that support. Otherwise, the support you'll be affording will be wasted and you'll essentially be a man down instead of .5 of a man up =)
Think about using items like Soul Shroud, Rylai's, Aegis of the Legion, Ancients Will, Starks fervor, and the Hextech Gunblade. When used properly, you may be able to net your team kills, keep your team in the battle for longer, or give your team a nice boost in fighting ability. Remember, it's not so much what hero you have, so much as how you intend on using your hero.