The ceiling fan you usually forget to turn on is an important piece of bathroom equipment. Good air flow has a number of advantages -- one of which could save you from relying on a stash of air freshening matches. The air in your bathroom doesn't only get stinky, it gets very humid, too. Humidity trapped in a small space like a bathroom will eventually begin to rust metal, like the hinges on your doors and cabinets, unless you have a consistent method for venting excess moisture. It can also cause mold and mildew problems.
There are lots of ventilation options available, from multiple units at stations around the room to the central overhead fixture arrangement you're probably familiar with. Provide your retailer, contractor or building inspector with the dimensions of your bathroom for guidance on sizing. If the location allows, you should also consider adding a window. Windows offer good ventilation as well natural light. They can make a small bathroom look larger, too.