Spherical skies can make a profound impact in a rendering and they really blow away 2D skies or Accurender’s built in skies and clouds. A spherical sky can add a lot of realism to your renderings because you get all sorts of beautiful sky reflections in your windows and if you are planning on doing any kind of animation work a spherical sky is almost essential.
I came across a great source for spherical Skies. This artist sells his stuff on Turbo Squid and does amazing work. They are totally seamless and absolutely gorgeous. Best of all you don't have to shell out $250 bucks to buy a package of 30 skies. You can purchase just the ones you need for $5.00 each. I have bought a couple and they are sweet!
http://www.turbosquid.com/Search/Ind...lAuthorExact/y