Turn the lights on, maybe throw a sheet over them to soften the light and then go close up on EVERYTHING!!! I have shots ranging from the floor boards to the light fittings. Not that they're any good but then that's more to do with my photography than anything else! Rain drops on windows can make good shots too...
Take landscapes but exclude the sky. Convert them to monochrome.
The flat light sometimes helps with monochrome pictures.
Shots like birds on the ground, waterfalls, waves on the beach. You don't necessarily want bright light and harsh shadows for that type of thing.
Oh i like that idea for setting up flowers (Still life). Ive jsut been around our my house with the tripod, the suns jsut going down at the moment so the sun comes directley through the windows, it looks lovley!