Earlier this year, Wizards of the Coast banned a number of cards from Magic, including the artifact lands. I felt this was a shame, because the artifact lands were a very elegant solution to the 'what special lands shall we produce' question. When musing upon this question, I thought of the following card, which I thought would have been an interesting solution if printed in Champions.
T: produce one colourless mana
T: destroy target artifact land
This would have created an interesting equilibrium as people put more of less into their decks as the metagame varied. I'm not sure if it would have solved the problem, but I would have been interested its results.