Alias offers free FBX SDK
Alias dropped the price of their SDK for the FBX 3D file format to zero.
This looks like a smart move on Alias's part. Since many of the companies supporting FBX are competitors to Alias, their support would wither pretty quickly. By making it free, it has the chance to become a de facto standard that everyone will continue to support.
The SDK was developed by Kaydara, which was purchase by Alias in 2004.
There is also a free program (registration required) to convert OBJ, DXF and 3DS files.