I recently checked out this app from my colleagues and it seems promising.
It imports the DWF file. The cool part is that not only you can navigate the model but you can measure the model just like Navisworks. See below.
I think this is cool because now this truly functions like what the other guy said in the other post "mobile BIM"
The only weakness I see right now is that it only imports DWF file.
I'm wondering if there are any other apps that can function as this one but can import files other than DWF.
Someone suggested 123d, but I don't think it does the measuring though.