Are you helping a child to make the gift? If the gift is from a child for a grandparent, parent or teacher, decoupage the child's photo on the outside of the jar, then trim the edges of the photo with lace or some other finishing type of ribbon. The child could even paint a little something on the opposite side of the jar or his or her little handprint with paint.
You can use already decorated type jars, or standard canning jars. The most common sizes are the pint and quart sized jars, but baby jars are also great for smaller portion drink or spice type mix gifts.
One common way to decorate a jar is take some fabric and cut a circle out of the fabric that is 6 - 8 inches across. You can use pinking shears or other decorative type scissors to edge the fabric. Lace can also be sewn as a trim to the fabric. Place the inner round section of the jar's lid on the jar and center the fabric on that. Screw the other section of the lid in place to hold the fabric. Fluff out the fabric where it comes out from under the lid.
Get creative also in the recipe instructions. Hang tags can be made either by hand, computer graphics or a label glued to the jar itself, but these can be customized to a central theme if desired. However you choose to do this, they will need the recipe's final instructions.
There are many wonderful recipes that can be made specifically designed for jars. These include soup mixes, spice mixes, cookie and other baked goods recipes, coffee and creamer recipes and so many more. These can be quite easy to make ahead of time, so you always have a gift you can grab whenever you need one, especially great for those last minute gift needs, or for the person who seems to have everything and is difficult to buy for.
You can paint the jar before pouring it with your ingredients. Buy paint that is specially for glass and follow the specific directions. Try finding a card or picture or something you'd like to put on the jar, and get it inside the jar to trace the design and add your own keepsake touches to it. This can really be used for a theme and the jar itself will remain a treasure long after the recipe has been used.
Layer the ingredients for a beautiful effect. Put at the bottom layers the finest ingredients, like flour but be sure to mix in the baking sodas, salt, etc that's called for in the recipes. You can use a funnel to help keep things orderly. If the flour dusts the rest of the jar, let it settle a while then gently wipe the jar with a paper towel before adding the rest of the layers. Brown sugar can be packed down to save a bit of space.
You can customize your jar gifts by either attaching with hot glue dried flowers, pinecones, beads, shells or whatever pleases you to the tops of the jars. Try tying small items with ribbon or raffia to the jars. Common items that work well are measuring spoons, tiny whisks, cookie cutter, ornaments, cinnamon bark, vanilla beans or any other small appealing items you may hunt down, get creative with this.
There are many beautiful ribbons out there and different styles and sizes of bows can be made and simply glued on to the lid. Lace can also be hot glued around the rim of the jar.
For a Victorian themed jar try a luscious tea mix or scone or other bakery recipe, gluing some lace around the rim of the jar, some small dried flowers on top or a tassel. Create a label or hang tag that looks like tea stained paper. For a western theme, try perhaps a bean soup recipe, wrap your jar in a bandanna, or use the bandanna itself as tied around the lid. Perhaps you can find a cowboy boot or hat graphic to decoupage on the jar itself, or paint one on.
What about the coffee lover? Try some small baby jars filled with different flavored creamers, cocoas and coffee mixes and put in a basket with a coffee mug and muffin or cookie. Paint the baby jar lids coordinating colors to match the coffee mug. Perhaps a great book would really top off that basket, and of course a touch of raffia or ribbon to finish it off.
Let your thoughts flow, there really is no telling what you can come up with for a beautiful gift to someone you care about that communicates that you really put forth some heart into this.