I know, it is waaaaaaaay too early for any proposal.
But you know how gaming forums are : cluttered with suggestion, every single craziest than the previous. It is still quiet, so here is my chance to speak !
To channel all that creativity, it might be fun, once the game has been released in a stable form and you have had some rest, to organise a "level design" competition. Of course as player, we won't be able to code anything, so to do so, there would be a specific canvas to fill (think as a "design document" with some hand drawn example levels and an explanation of the generation, maybe some special tiles, monster, scripted events), so things are somewhat organised and ideas should be relatively well elaborated.
And the selected levels would be implemented of course...