Neighbirds by Andreu Carulla are pretty good looking modular prefab birdhouses.
Carulla about NeighBirds:Modular birds’ nest that helps baby birds’ emancipation, as it creates a close knit neighborhood. Easy installation in either wild or urban environments, as it can be hanged onto a branch, a structure, a hook or a wall. A way to get birds closer to your home bond with your kids as you teach them love for nature and wildlife observation.
Handmade of untreated pinewood with a removable little branch for birds to stand on. The little branch is the organic touch that makes it familiar to birds. You can remove it and change it to your preference.
All images © Andreu Carulla – Website