Set yourself up as an expert on something that you want to talk about. Make stationery and send a press release. Be rational and sincere. The equipment needed to set up a micro-station is cheaper and easier then you might think. The laws and licensing procedures for such low-watt stations are currently under debate, so you need to be prepared for a fight.
Mobile stations are also a possibility.
Sell yourself to non-commercial radio. Get involved in your local non-commercial station. These community stations are usually open to new ideas and are always in need of volunteer help. You may have to start at the bottom and work your way up, but with many of these stations, that might not take too long. Infiltrate Big Radio.