First and foremost, submit your top songs to Clear Channel. This indexes to a couple hundred radio stations. http://www.iheartradio.com/new2/signup/index.html.
Second, a must is also – http://www.thesixtyone.com.
And of course, http://ReverbNation.com.
http://www.jamendo.com This is an awesome way to get some free exposure across the globe. We have songs played through the licensing agreement in France, Spain, Australia, Japan, and more. We have songs in two Australian documentaries as well. People can download your songs for free though, so we waited for a few months after we sold a bunch of CDs to upload or full albums. But it also indexes really well.
This is hit or miss: http://one-track-mind.com
Not sure about this one, but it’s worth a shot for the social media saturation, if you feel like learning how to do it like the pros. http://headliner.fm
These are constantly changing, so I will update you with more as soon as I collect the top ones that I have received feedback from.