I definitely think it is okay to meet people you speak with online in person, but you want to be extremely cautious. Get to know the person really well first, both personality and making sure they are the physical person they say they are. It also helps if you get a chance to interact online or by phone with that person's friends or family to get more of an idea of what kind of a person they are. This way you can more easily assume that they are not trying to trick you or do something bad (by keeping your interactions a secret from others for some reason).
Trust your judgement and be extremely careful, but don't miss out on what could be a life-long friendship or romance by being bogged down with fear.