Frequently Asked Question: How do I get my music played on the radio?
I have some experience with internet radios.
I use a service, that submits my tracks to a number of smaller and larger radios called MusicSubmit. I find the pricing is ok. In my experience you can count on 5-10% of the radios to play your tunes.
I do think though that it doesn't hurt to do some research yourself and to submit to radios directly, e.g. to the radio stations that can be conveniently accessed through iTunes. It's a bit tedious and you have to be a bit diligent but the personal contact that sometimes evolves is a good thing. Also not all radios are connected to MusicSubmit, especially the larger ones. There is also a fine directory for internet radios called ShoutCast. Apart from that – as so often – Google is very helpful.
And not to forget my favorite kind of radio: the podcast. I like them so much, because I can listen to a show several times and if I find it boring or I don't want to hear the talking I can fast-forward. Of course there are podcast directories, one of them is PodcastAlly. I think you should limit yourself to the top 50 podcasts in the genre of the tracks that you want to promote, otherwise you might have only a few listeners when the track gets played.
In the beginning I felt a bit uncomfortable contacting the radios directly but many DJs reply very nicely (of course there is an asshole among them once in a while). That way you already have a great contact that you can send your tunes to next time.
Some radios don't like emails with download links, they prefer CDs or even better a whole press kit. In my opinion you should be careful to which radio you send something because you might spend more time and money than it'll ever be worth. But sometimes it can be really worth it; one time I did send a CD to someone and he started to play it on three radios, one of them a satellite radio. Also the personal contact is there.