PB

PB (packed model) is the model format used by Atlus in Nocturne and some other titles. Along with PB you may also find some other model formats, such as: MB - model format, unlike PB it is unpacked AB - animation format, some models have it unpacked, usually in the same folder as MB model TB - textures format container, has TMX textures inside it

PB 3DS MAX importer
TGE created a maxscript that's intended to be used with Autodesk 3DS MAX. It supports importing PB, MB meshes, rigging, materials. You can get it here. Skinning or texturing information may not always be perfectly retained and models may require manual tweaking.

DDS3-Model-Studio
DDS3-Model-Studio (or DDS3ModelConverter) is a tool for converting skinned models to formats such as DAE, OBJ, FBX. Rigging and mesh/texture conversion is currently possible. You can download the latest build here, or get a version that includes DniweTamp's windows .bat script for mass converting of PB and MB models to all three formats, DAE, OBJ AND FBX here