I let this one slip under the radar last month but I would be remiss without mentioning the recent (May 16th) release of Ayam 1.8.2, a free 3D modeling application which includes a IRIX 6.5 MIPS3 build amongst other various platform binaries.
For those who haven't heard of Ayam, it's an open source (BSD-license) 3D modeler featuring CSG (Constructive Solid Geometry), NURBS (Non Uniform Rational B-Splines), Bilinear and Bicubic Patch Meshes, Poly Meshes, Subdivision Surfaces, Metaballs and many import/export formats. A more comprehensive list of features can be found on the Ayam website. From the news page it appears that development is still at full steam with the CVS version now handling Wavefront OBJ files amongst other features.
http://ayam.sourceforge.net