Andreas Reimer sent me a quick little note to let us all know about HDRI Hub and some freely available HDRI Environments that they have posted for everyone. the HDR Images are actually packaged up, conveniently I might add, as a sIBL, allowing you to install them right through HDR Labs sIBL and uses them just like any other environment.
HDRI Hub is pleased to provide you free HDRI environments that you can use in your private and commercial projects. Our focus is on producing great quality maps with a very high dynamic range to help you with photo realistic lighting and shading
A Smart IBL actually consists of three elements packaged in a directory with a description file linking a high resolution panorama as the camera background, a high resolution HDR as a specular component, and a blurred low resolution HDR as a diffuse lighting environment together.
It is also worthy to note that HDRI Hub are running a promotion through January that offers 30% discount on all purchases, until January 31. Use the promotion code “JAN-2013” during the checkout. This sales promotion can not be combined with other promotions – Check out HDRI-HUB for more information.