Scott distributes directly to Amazon for CD and MP3, and directly to Google Play Music for MP3, and directly to Bandcamp for FLAC, OGG and other formats.  Those three sites are cool because they allow this.  For other sites, he used TuneCore for a while, got fed up with their software and prices, then switched to CD Baby - but mainly for the "get your songs in iTunes" part.  They are an aggregator who also send out to Spotify, and other popular MP3 download and streaming sites (in addition to also selling CDs).

Here is the Scott Cooley page on the distributor's website:  http://www.cdbaby.com/Artist/ScottCooley, and here is a screen shot of the stores selected for one of the more recent releases:

That's not all.  The MP3s page of this site shows many more online music download stores Scott Cooley albums have been distributed to over the years.