XSI 6 Mod Tool
The Softimage XSI 6 Mod Tool is a completely FREE 3D modeling and animation package that plugs right into Microsoft XNA Game Studio Express and Valve Half- Life 2... but it does not only do that, it fully support COLLADA import/export thru Crosswalk. This means that it does include the leatest COLLADA plugins and will also benefit from the frequent Crosswalk updates. The only limitation on that side is that you're limited to geometry of 64000 triangle at export. No limitation on import.
For more information on that product see the Softimage XSI 6 Mod Tool page: XSI 6 Mod Tool
For information releated to the COLLADA plugin of see: Crosswalk