While some older jars are more valuable and some people are serious collectors, any jars you have on hand will be a free way to wrangle your small stuff. (If you want to start collecting them, you can also get good deals through Etsy.) Here are a few ways to use jars that aren't in a special collection or a hot water bath:
Vase: Why buy a vase when you essentially already have one on hand? The fastest and cheapest way for canners/collectors to get those flowers in water is to pull out a Ball jar.
Candle holder: Canning jars are made to withstand high heat. Add a small candle to a jar, and you have a pretty, unassuming light source. By wrapping wire around the mouth of the jar and creating a handle, you can make lanterns. They're more decorative than organizational, but consider it "candle storage."
Utensil holder: In my kitchen, a wide mouth quart jar holds my most-used utensils. The opening is big enough to accommodate my spoons and spatulas, but not so big that things flop around or topple out. Utensils used less frequently are kept in a drawer.
Dry food storage: One of the open shelves in my parents' kitchen is lined with antique blue Ball jars with zinc caps, and they are filled with everything from rice to tea bags. Store your small dry goods this way, and you'll be able to find things more easily. Faith from The Kitchn uses canning jars for grain storage, and she points out that you want to avoid keeping them in bright light.
General food storage: Just because the jars are made for canning doesn't mean they can't be used for the rest of your food. Try using a smaller size jar for a yogurt parfait to take to work for breakfast. You can also use them to store leftovers or homemade salad dressing.
Piggy bank: Keeping your change in one place is an act of self-discipline. Try using half pint or pint jars to keep track of coins; separate out the quarters, and you will have a head start on laundry day.
Craft organizing: One night I went a little Martha crazy separating my button stash by color and then putting them in jars; at least now I can always find a green one. (You can go one step further and cover the lids with paper scraps.) The idea of course works for other things like spools of thread, markers, etc.
Know that one possible drawback to using canning jars is the top. Current American-style, two-part canning tops are not practical for longer-term food storage unless you have processed them in hot water. As-is, they are not truly airtight. Second, for food safety reasons the lid (flat part) is meant to be used only once, and it is annoying to use them for something like leftovers only to realize you don't have enough left for canning. From doing that, I have wound up with way more rings (which are reusable) than lids.
There are, of course, alternatives: try Ball's antique zinc lids or their newer reusable plastic lids (not meant for canning). For something like craft or coin storage, you can just glue the flat lid to the band. Lastly, you can try a different kind of jar altogether, such as the ones by Weck, or any empty glass jars (I like the shape of the ones for Maille mustard and Bonne Maman jams).
Images: 1. BitofButter 2. Chelle Paperie via Apartment Therapy 3. Leah Moss for Apartment Therapy 4. Faith Durand for The Kitchn 5. Tara Greenfield for The Kitchn 6. coffeeteabooksandrecipes 7. Shelteriffic 8. Martha Stewart 9. Krzy4Btns 10. Collectors Weekly