Oven doors - use a dishwasher tablet. If it has film on it then you need to unwrap it. Dip it into some water and then rub it over the oven door. Keep re-wetting it. You might have to use a couple but it loosens off all the crap really well. Also works on burnt marks on saucepans and hobs.
If you've burned food into a saucepan then fill with water and simmer with a teaspoon of bicarb or washing powder - lifts it straight off with no scrubbing.
If blue-tack has left an oily mark on your wall, then apply some lighter fluid onto a clean pale tea-towel or cloth and very gently rub at the mark.
If you have small scratches or muddy marks on your painted walls, then use a small amount of cream cleaner on a pale cloth or tea towel and gently rub the mark. Leave to dry and then brush the wall off with a clean dry cloth or tea towel.
Small scratches in glass can be buffed out using toothpaste.
A squirt of WD40 will remove all sticky label residue.
If you store seasonal clothing in boxes or bags, then stick a tumble dryer sheet in with them - stops them smelling musty.
If your washing machine smells and is a bit gungy and mouldy then get some washing soda crystals - usually in the same aisle as cleaning or laundry products. Put a cupful straight into the drum of the empty machine and run it at 90. Then when it's finished, put a cupful of white vinegar straight into the drum and run it again at 90. Cleans all the gunk out and deodorises the machine as well.