What are you finding so Difficult?
If you've got the music and the Producers and a Release Schedule and A Good Network of DJ's and Blogs or Whatever To Send Your Music to Then You've Already Done the Difficult Part M8.
Digital Music Distributors Are Ten-A-Penny M8 it's Not that Hard To Find one, In Fact I googled for "digital music distribution" and Found A whole Bunch of Them.
What Do you Mean by "useful" Anyway?
You send the distro your Hot Trax in .waV format and Fill In some metaData to Explain who made said Hot Trax, then the distributor Will Send those Hot Trax out to different Shops. They all Do the Same thing afaIk. The only Difference is which Shops your selected distro will stock, and what Percentage of the sales price you Get.
Google "digital music distribution" and you'll find loads of them who all Do The Same Thing
