Hello there. I have a WHOLE list of ideas I want to do, but they are not for "boys" they are uni-sex, since I do not know the sex of mine!
The outer-space one was an idea I had too! I think its great and imaginative. The baby could grow up in a room like that, and I believe it promotes imagination and creativity!
Here are my others:
1. Cute bugs in a garden (not creepy bugs, cartoon ones with sweet faces)
2. Turtles - green room!
3. Teddy bears
4. Clowns
5. Winnie the Pooh
6. Petting zoo (friendly animals)
7. Farm - you can paint fences on the walls and have a barn, clouds on the ceiling, etc.
8. Puppies.
9. Under water. A nice royal blue with fish EVERYWHERE! You can suspend some from the ceiling with fishing wire to give the illusion of being underwater! (This is my favorite)
10. Forest - all green and brown - friendly bears, birds, bees, etc
11. Dr. Seuss - a little scary, but different!
12. Jungle - Paint huge trees on the walls with vines, add monkeys, tigers, parrots and so on! Dont forget a canopy of leaves on the ceiling!
These are my favorites so far (in no order) and I hope this can help a little! Your idea is wonderful, and good luck with it!