Okay, it's cold outside--in most places. Either way now is a great time to take care of some things on the inside while you are trying to sell your house--every little bit helps. For those you you not selling, these things will help keep your house in working order as well.
One area I usually think I do a good job on is the kitchen, but I usually forget about the refridgerator. Pull the fridge out and clean in the back--nasty, I know, but necessary! Wipe off the coils and vacuum back here--don't forget the front grille area where lots of dust collects as well. I usually find some important phone numbers written on sticky notes back here too! If you are planning on moving, you need to clean back here anyway if you are taking your fridge.
The oven. "Self-cleaning" appliances are nice, but nothing can replace a good scrubbing. Trying to sell a home with dirty ovens and ranges is much harder! Perception is everything: If a potential buyer thinks you maintain your appliances well, he or she might think you maintain everything esle as you should too. Keeping grime and nasty food build-up away from elements and gas burners lets your appliances function better too. I think you will find that those older appliances don't look as old when they are clean! Remember, if you aren't going to replace something before you sell, make it spotless and work as it should.
Garbage disposal. I usually overlook this one, but they need maintenance as well and not just when they start to smell!
Don't forget to change your air filter to keep your system running smoothly and you breathing easier. Also, go around to all your vents and pull them out. Vacuum down the vent as far as you can go and then soak the vent covers in a cleaning solution.
Have a fireplace?? The fireplace is usually the focal point of the room it is in. Even if you have gas logs, I am sure you have noticed dust and pet hair, etc. collecting here. Buyers will certainly be inspecting your fireplace and it should be spotless. If you have a wood burning fireplace, you should take time to clean the bricks as much as possible. This can be time consuming, but it can really make a difference.
The dreaded attic! I know, I know, you only go up there to hide Christmas gifts and to store things you think you will need 20 years later, but you can clean some here too. If you have pull-down access to your attic, remember, buyers will most likely be going up there for a look. Pull down the stairs and clean and vacuum along the stairs to get rid of dust and old insulation that can make attic access areas seem nasty.
Naturally, there are thousands of things to clean in a house and these are only a few. Just remember, anything extra that you can do is something a potential buyer won't have to do. Have fun and good luck!