Firstly, I won't be able to continue any of my project for two weeks, 'cause I'm going to the USA tomorrow (school exchange, yeah!).
Secondly, I finally got my super fast (due to 8 bit assembler LUT function and coordinate transformation algorithms) flat tilemapper for any size of map ready:
(again, better grey on calc)
The program lets you enter the size of the tilemap (only square maps, but other arbitary formats aren't any harder to implement), then it generates some random grey/white tiles and displays it on the screen. You can scroll around with the arrow keys.