What's the worst thing about Penzeys spices? They're labeled on the side of the jar but not on the lid, so you have a choice: put them on a shelf near eye level so you can paw through them like a barbarian while searching for something at the back, or put them in a spice drawer so you can lift each jar with hope in your heart before dropping it in disgust as you've once again forgotten which was the cinnamon. Or maybe the problem is that they nestle together so closely in a drawer that you can't get fingers in between the lids to lift anything out anyway. That second problem is easy to solve: get a pice of masonite, thin plywood, or other material to make a drawer insert and cut a grid of recesses in it, 1 15/16" in diameter, with a small chamfer at the top edge. That will keep the jars aligned with finger space between their lids. But you still need to know which jar is which, and for that you need labels.
What should a spice jar label look like? It should have the spice name prominently displayed of course, and with high contrast so it's legible at a glance and in poor lighting. Combined with Penzeys jar lids being black, this suggests a black label with white text. A full-bleed label in black also hides any registration problems, either with printing or label alignment. Spices should also be labeled with their purchase date so quantities can be adjusted as they get old, and old spices can be replaced. Additionally, if the label accommodates several dates, then you can get a sense of how quickly you use particular spices, and can adjust how much you buy at a time. Also, you won't need to reprint the label every time you replace a spice.
How then to accommodate a bunch of dates on a black label without detracting from the basic simplicity of a white spice name on a black background? You don't really need an exact date for spices - an approximation will do - so how about just a month and year rather than a full date? You could leave some white areas to write MM/YY every time you buy spices, but I don't like how that looks, and it takes up quite a bit of space if you want to be able to write several dates. It's doable: three boxes above and three below the spice name, but it makes the name feel cramped. The best option I've come up with is to reduce monthly resolution down to quarterly. There are four quarters, and four digits, in a year so that fits together nicely. And now you can have small checkboxes rather than a large space to write a date. As it happens, ten full years worth of quarterly checkboxes fit nicely in a ring around the label's perimeter.
But what to print on? Penzeys half-cup "A" jar lids have a small recess on the top that's around 45mm in diameter, just over 1.75 inches so that seems a good size. Round labels are more readily available in a 1.5 inch size but the extra space is worth the hunt. I've used Online Labels' OL914LP Weatherproof Polyester Laser labels which have a nice smooth surface that results in an even black background when laser printed. If you've ever noticed how large black laser printed areas on office paper are a bit blotchy and uneven, you'll appreciate the polyester surface.
You can download the Inkscape SVG of the spice jar labels I made to change the names to match whatever spices you have. I'm using a font called Himalaya; if you don't have it, you may need to adjust the line height so the multi-line spice names look nice. Also, remember to hide the layer with the white circles on it before exporting to PDF for print, or you'll get bits of white circle on your labels showing you exactly how much misregistration and page skew you have in your printer's paper path.