FCollada

FCollada is an open-source C++ library which offers incomparable support for COLLADA interoperability. It is written by Feeling Software and is used within many commercial products and engine as well as Feeling Software's ColladaMaya and ColladaMax.

ColladaMaya is Feeling Software's COLLADA import/export plug-in for Maya. ColladaMax is Feeling Software's COLLADA import/export plug-in for 3dsMax. They offer unprecedented inter-operability between these and other DCC tools and allow for painless and fast extraction of data from Maya and 3dsMax.

Links:
ColladaMax extensions
ColladaMaya extensions
FCollada extensions

External links:
Feeling Software
ColladaMax info-sheet
ColladaMaya info-sheet
FCollada info-sheet