These titan-esque models are called Leviathans and Dreamforge is in the process of casting and creating an entire line of them. The main difference between the models so far has been the heads (the skull above and the Crusader helm below + numerous CAD designs on their site). The titans also have different weapon arms in the CAD designs, but the only one I have seen so far in photos is the Vulcan Cannon, which looks exactly like a GIANT assault cannon from 40k.
While that seems like a crazy "ballin' outta control" kind of idea, it could be the ultimate conversion and would certainly be a centerpeice on the old Apoc table! The question would be whether or not Dreamforge would sell the individual weapons or only complete Leviathan kits?
So, if the model shots interest you, check out the Dreamforge blog and tell them what you think. In the meantime, what are your thoughts on titans? Are they a must have (or at least a must fantasize about) model for you? Are they so far beyond the realm of feasability in terms of money or storage space that you would never own one? Would you rather have a second army or a titan (pretty much where price puts us)?