im sure you get a 1002 suggestions a day on how to improve what is already an awesome game. So here is mine :)
fields are one of the more interesting aspects on the editor, but are a pain to position. It would be nice if I could highlight an entry in the field movement window and then click a subcell and have it populate the position instead of having to note the position and type it in. I havnt created a whole lot of maps (ok, only 2) but one of them has fields that redistribute creeper like a stealthy version of phantoms. I would have created a whole lot more spawn points but it got a little tedious after a while...
looks like someone else asked the same question here:
http://knucklecracker.com/forums/index.php?topic=8797.0
sorry, should have searched a little first.