1) The fuse box in your apartment or condo is very important, but not very attractive! Create a hinged door using a chalkboard, painting, or large framed photo.
2) Your thermostat is essential to daily life but it typically isn't a style object. Try covering up with a press-board "cigar" box. Cut a hole in the box's lid large enough for the thermostat. Next screw the lid to the wall around the unit allowing the box to act as a cover that can be flipped up! You can decorate the outside of the box as you would like to match your decor! You can also cover your thermostat with a deep stretched canvas. Using a level, measure and place two nails on either side of the wall next to the unit. You could even use push-pins if you're a renter. Next hang the appropriate sized, decorated deep canvas over the thermostat.
3) We all have speakers these days with surround sound systems for our TVs and other speaker systems for other audio systems. These speakers are getting more eye pleasing but they often times still do not blend into your decor. For small wall mounted speakers, you can create a deep box from pine framing. You can then stretch any light weight fabric over the frame like an artist canvas and staple it into place. The sound will pass through the fabric easily. If you have larger, floor speakers from older stereo systems you can also spruce these up. Create a box from 1/4 inch plywood and add a piece of lattice to the front of the box. Of course the back of the box would be left open to allow you to slide the cover over the speakers. Paint the cover to match your home.