Really the sky is the limit on what you can do. What services or information areas are under-serviced in your state/province? You might consider looking at news, but first make sure that local T.V. and newspapers are already not offering mobile news services, because they can likely 'beat you up' in terms of types and regularity of news updates.
Is there a niche market or area in your province or state that you have knowledge about? If so, then maybe consider doing something in regards to this niche area.
You need to find something that people will want to visit on their mobiles.