The service still appears to be very much a one-man project. Musicians are able to upload tracks, mark them as Creative Commons/free or copyrighted, build dedicated sections to promote their bands/music, collect "tips" etc. Users are able to download or stream selections and buy selected tracks or tip musicians that offer free downloads.
Although Marken's project has been in service for nearly 10 years in one form or another (as ArtistServer since 2005), the site offers somewhere in the range of 15,000 songs. It appears that Marken is soon set to launch version 2.0 of the service.
The music available here comes in many, many genres: some with many more selections, some with considerably fewer: Country/Bluegrass lists only 3 songs; Jazz/Fusion has 49. The quality is ... mixed. There is plenty that is good - and some that is considerably weaker. This is fitting for the stated goal of the site: the site aims to provide a resource for musicians, and musicians are responsible for what they post.
You can find music by the acclaimed Dutch group Klimt ! String Quartet (in the Jazz genre) that is (as AllMusic notes) "a delightful release combining experiment and entertainment in a way at which the Dutch seem to excel."
Klimt! String Quartet: Kiss The Guitar Player
You can also pick up your own free copy of music by "chongjohn57", a musician you'll also find at Jamendo (last post) and SoundCloud (another previous post). Here's a link to I Got You.
ChongJohn57: I Got You
I think you'll find it worth your time to do your own deeper digging into ArtistServer
