I bought a liquid plant food sprayer with a hose attachment. When the disposable plant food bottle was empty, I opened it, rinsed it and filled it with chlorine bleach. It now attaches to my hose to clean mold off the deck and patio.
Whenever I run off copies of something on my computer and there is a mistake or after I am done with the paper, I fold it into fourths and tear along the lines. These small sheets are just the right size for making grocery lists, reminder notes, etc. Then, when I finish with these, I put them into the recycling bin. That way I've recycled them twice!
I clean all glass jars from pasta sauce, pickles, etc. and reuse them. With the cost and health issues of plastic food storage containers, I feel better about putting leftovers in glass containers. Just be sure to underfill if you will be freezing, as food expands when frozen. This also keeps glass out of the landfills a little longer :)
Instead of constantly spending money on food storage bags, I reuse the plastic bags from marshmallows, bread, etc. I also use the plastic bags that are in empty cereal boxes. No, you don't have the 'zipper' on the bag, but I bought a package of clothespins from the Dollar Store to hold the bags closed.
Keep empty cough medicine or any liquid medicine containers for travel-sized shampoo, conditioner, body wash, etc. Most of these are completely spill proof, and you can toss them before returning home to make room for more souvenirs!! I even use one for soap slivers -- just add hot water, shake, and I have my own liquid soap.
If you purchase bulk liquid laundry detergent with its own spout dispenser, don't throw the bottle out when empty. Fill it up with water and set it outside in a cool spot near a door. This is great for a quick clean-up of dirty little fingers and feet, plastic toys, or just about everything. The small amount of liquid detergent left in the bottle is just right for a more thorough cleaning than just water. It can even be set out in the sun for a warm sudsy handwashing if desired.
When I empty my dehumidifier, I either use the water for my outdoor/indoor plants if needed, or put it in my washer to be used for the next batch of laundry.
The new vacuum seal bags are great for freezing but can be expensive to use just one time. Wrap your raw meat in freezer paper and then place it in the bag. This not only allows you to reuse the bag, but it prevents the liquid from the meat from getting into the sealer too. Just remember to write the contents on the freezer paper so you know what's in the bag.