I wanna make my next tank look industrial, have smokestacks, and pipes the betta can swim through and hide in, a little mothballed factory covered in plants ... An old, disused power plant!
(The tank I have now is all natural, stones, plants, driftwood, so this will be the complete opposite in essence.)
You could make an old village with a river pretend-powered by a water mill. The river effect can be achieved with different coloured gravel and river stones. The most amazing river/creek bed (and all around awesome tank) I've seen is here:
At about 1.50 he shows the creek bed from the top so that you can get a good look at it.