I know you're keen on tile-based engines (tiles are cool, that's a fact). But no one likes to develop brand new tools to fit his/her own project. That's why I gave a try at some kind of "limitless, flexible, universal" tile-based map editor (and more generally, a quite complete file format to handle that). Right now, I have a functional tool with a few nice features such as dynamic map sizing, file-based tile selection and full map-shot.
The output format can only be TMF (detailed in doc). The structure allows high amount of unique tiles, huge maps, multiple layers and entity placing and should be very easy to open and convert to suit your own needs.
Note that the stuff only supports BMP for now -- which can be RLE-compressed, using indexed palette (2, 16 or 256 colors) or hi-colors (16 or 24 bits). In fact, T-MapEd is still under development. Feel free to try it out, report bugs and make suggestions.
Minisite here right here
JILL tools here (did I mentioned it is a completely forgettable classic by Epic Mega Games? -- I didn't forget it, somehow)
T-Map'Ed BR2 http://gaarabis.free.fr/_acc/t-maped/3d ... ild_02.rar (can't use the URL tag, sorry)
EDIT: New version, now support multiple layers
RE-EDIT: Sorry, it's only me... again... 2nd Beta released, with conversion tools for the Jill Trilogy (Jill of the Jungle, Jill Goes Underground and Jill Saves The Prince), coded in FB also. The goal is to show that the editor can be used with pretty much anything that uses tiles.