Internet Radio
When thinking about Internet radio don't consider just buying ad space during one of the more popular shows. Internet radio can be an amazing way to market your practice online whether you choose to be a guest on one of the many available shows or you choose to DJ a show on your own.
As a guest you have the benefit of connecting with an already established audience that's tuning in because they like and/or trust the show host. Depending on the format of the show you may be interviewed by the host of the show directly or you may be asked to field audience questions. Be sure that you know what you're getting into before you agree to do it, and make sure that you listen to the show in full a few times so that you can be comfortable about what you're agreeing to do. If the show has a format where the same group of guests are invited back repeatedly to serve as experts it may be an even better opportunity provided you can commit to the times you'd be needed.
As the DJ of your own internet radio show you'd be responsible for creating your own content and setting the structure. This allows you a little more freedom then being a guest but you have to very careful that your show doesn't sound like one long commercial for your practice. You also have to make sure you have the time to commit to creating and implementing a radio show.