There are a couple of map packs hanging around that you can download, Otreums for one. http://www.mbrepository.com/file.php?id=2292
But on another note to add the maps you downloaded:
make a copy of native in your module folder then get all the sco files you want, rename it to to multi_scene_1, (2 4 or 7) and paste them on to your desktop.
Now open up your native copy and then Scene_Obj and paste them in there. Start up your native copy and they should be under ruins, Village and whatnot. If you want to rename them then go to scripts.txt in native copy and Ctrl+F (search) for multi_scene_1 then next to it is what the game refers to them as, type in what you want in place of it eg. ruins becomes wercheg_cliffs and make sure you have these _ instead of spaces. Then hit save and the names should change in-game. This is mostly for testing purposes of course, to actually add them to native you need to go through a lot more than that. If you want I could direct you to a tutorial for adding them with the module system?