This was already touched on with the comment about Shanty Towns being like labs and the comment about using them in a non-terminal engine, but Shanty Town seems to me like you could build your deck around it and only it and draw a whole bunch of cards. Maybe. If you're lucky. And then, it would benefit, logistics of getting it aside, from Diadem. Unless you have some sort of terminal in your deck. I think you'd want it to be non-drawing. Hey, maybe Mandarin could go here! But really, I haven't tried this at all.
Regarding Develop, it really just needs the board. My brother won a game (IRL) by using develop to increase his deck size and win with Gardens since it was the only card in the game increasing your number of cards. (No plus buys, no gain cards, a whole whack of trashers). In the same game, we noticed an interesting combo with Develop and Expand: Develop a Gold into a Duchy and an Expand, both of which are on top of your deck. Next turn, Expand the Duchy into a Province. (In this game, some of the golds were supplied by Upgrading, Remaking or Developing Upgrades. I told you there were a lot of trashers.) That being said, I don't think develop works much of the time.