Some day I'll see what Gimp has to offer, but for now, I won't even bother checking into Mosaic Maker. It's just not complex enough for interior design.
Here is what I've been able to make up for a couple of friends I am helping right now:
|Basement Family Room, by Larsen Interiors|
|Dining Room by Larsen Interiors|
This is such a great way to inspire and communicate with clients!