Also, if you have lots of used tea bags keep them very cold in a fridge or frozen in a freezer. If left in a warm environment bacteria and mold can spoil them.

• You can wipe mirrors and windows with used tea bags then buff try with a clean soft cloth. The tea's tannic acid leaves the glass sparkling clean…with no chemical smell like you get from commercial products. Alternatively, make a weak tea solution with used tea bags to spray on glass surfaces and buff dry with a soft lint-free cloth.
• Add used teabags to warm water and soak your feet in them to neutralize foot odours, soften calluses and nourish skin.
• Place a couple of teabags in an open container in the fridge to get rid of odours.
• Wiping cast iron pans with a damp used tea bag after every use will help keep them rust free The tannins in the tea form a protective layer that prevents oxidation, which causes rust.  
• Pasta, rice and other grains take on a new delicate flavour when a used tea bag is added. Hang the used bags into a pot of water while it comes to a boil to flavor the water, remove used tea bags, then add your pasta, rice, or other grains. Try experimenting with various teas, like jasmine, chai, or cinnamon spice.
• Open and empty used tea bags into your compost bin or around garden plants. Tea bags add a nitrogen component to balance other carbon-rich materials.
• Flavour your meat with used tea bags or even leftover tea. Marinade your poultry, beef or lamb in a mixture of weak tea and water or wine for a few hours before cooking. The tea will also help tenderize your meat. 
• You can flavour meat with used tea bags or leftover tea. Marinade poultry, beef or lamb in a mixture of weak tea and water or wine for a few hours. The tea also helps tenderize the meat. 
• Cool two used tea bags and place them over your closed eyes for about 15 minutes. The tannins in the bags will reduce puffiness and feel very soothing.
• A used tea bag is great for a sty on your eyelid.
• Rub used teabags on white paper to stain an old parchment type of paper for a treasure map for your children.
• Mix dried used tea leaves into cat litter.
• Add a few drops of essential oil to dry used tea bags to create air fresheners for your home, office, or vehicle. Some tea bags come with a string built in, which would make hanging them is a snap. After the oil wears off, you can add a few more drops to refresh. Tea leaves absorb odours, so these homemade air fresheners will work double-time to keep your living areas smelling great.
• Mice don’t like the smell of tea. Tuck used tea bags in cupboards and pantries as well as areas where they might enter your home. They'll think twice about coming inside. To make the deterrent even more effective saturate the bags with peppermint essential oil. Not only will this further deter rodents, it will also repel a variety of other household pests like spiders and ants. And as a bonus, your home will smell minty fresh.