One little frugal gadget I have is this soda pop top. I picked it up somewhere for $.50 and it has probably saved me, oh, dollars over the year. It goes like this: You open a soda and start to drink it. Then something comes up and you have to go somewhere or do something that is not soda friendly. Normally in this situation you would lose the soda since it would go flat. However, this little gadget lets you put a top on the soda, which keeps the carbonation in so you can enjoy your soda later on. I imagine this would also be helpful if I had kids and let them drink soda.
Although you can order soda pop tops online, most major stores also carry them. I think I got two for a dollar at a local dollar store. I recommend it if you are a soda drinker who occasionally finds herself on the verge of wasting a soda.