I find the test illustration more the work for an illustrator then a cartographer, there's a thin line between the two, but worth the distiction. It would be helpfull when publishers are looking for freelancers to specify what kind of work they are looking for, the test image helps a lot, but what about dungeon maps, need these to be also 3d?
Also of interest to people wanting to reply to this call is what time frame your looking for artists, some people have a schedule or have already been booked until a certain time.
More specifics saves both you and the freelancer a lot of valuable time.
I also don't advertise jobs by saying: "Looking for a programmer, for both the windows and the linux platform. Send examples and include rates." If i advertise like this, a lot of good programmers that i would be looking for wouldn't even bother to apply...
Sorry for the rant, just trying to be helpful.