File formats (*.obj, etc) suitable for mobile?

Hi, what are the (binary) file formats that are suitable for mobile devices like the iPhone, Android, etc.?

From my understanding, the Wavefront OBJ format seems to be the best choice as it is free and easy to implement. However, since it is basic text file and lacks support for shaders, I am thinking if there is something similar but with extended support, i.e. a compressed OBJ file with some additional containers defined for shaders?

I have thought of COLLADA, too. But in their web site they say it is more suitable for an exchanging purpose amongst 3D editing software rather than for end-presentation.

What do you think or best, what are you using?
Comments highly appreciated.

Thank you.

OBJ works fine, it supports materials and if your clever you can use that as a guide to load separate shader files and textures.

The most suitable format though is the one you make yourself, though you will have to write a converter.

Thank you for your suggestion.

I will start with OBJ then and extend it gradually to finally make an original format

Thanks.