I'm in the middle of re-vamping my level design system. Thank goodness i didn't get too far with version one before realizing that another version would be necessary. Version 2.0 will not use a tile-based system (like most older-style NES/SNES platformers) but will use a combination of Minecraft-style chunks, polygonal collision data, and multiple depths (allowing the player to explore along the z-axis as well) for a smoother and more realistic experience. Working on it hard today and tomorrow, might post a pic of the level editor later on.