StudioGPU has made their flagship renderer MachStudio Pro 2.0 available for free with no strings attached, and no personal info needed.
* Real-time rendering on your desktop
* Groundbreaking levels of interactivity
* Manipulation of cameras, lighting, ambient occlusion, animation, and materials in real-time
* Seamless interoperability with most leading CG software programs including Autodesk Maya and 3ds Max
* Resolution independent, allowing renders at any resolution and format (e.g. 1080P, 720P, 16:9, 4:3, NTSC, PAL and even 2K and beyond)
* Render as final frame, or as passes for additional compositing work
* Generate higher quality CGI results for less time and money