There really isn't much out there.. lysol will probably always know more about them than me but here's the basics:
you can get lasered, pad printed and dyesubbed keys. if you want the PBT dyesubs you need to look for model # 410xSPAUS where x is some number. Mine is a 4101SPAUS, not sure if they did other dyesubs with a different number.
You can find the switch+PCB assembly alone on ebay here and there -- it has no controller but you can either drop the whole board in and solder the connector in or just swap the keycaps -- probably easier. also keep in mind that newer ML boards have different bottom rows (win/menu keys and a smaller spacebar).
i've been trying to get people to make custom ML caps (mostly transformers but i did once PM mr. clack... no response

) ). been thinking about doing some molding this summer with JesusWasAZombie so we'll see

Lys- er, Ivan

Do you have any ML boards with that foam dampener? How does it feel?