Thanks to Cool Tools for their recent overview of wide mouth canning  jar accessories.

They covered:

• The Cuppow: A lid that lets you drink from your canning jar.
• The Kraut Cap: An airlock for a canning jar for anaerobic fermenting.
• Re-Cap: A pour spout and lid for a canning jar. This would be great for salad dressings.
• The Holdster: A handle for a canning jar.

I would also add these other accessories that extend the usefullness of your canning jars:

• The Bnto from Cuppow: A cup that fits inside a canning jar, giving two separate storage spaces.
• Plastic jar lids: Dishwasher-safe and reusable lids for foods that are NOT shelf stable.
• Shaker jar lids: Turn your jar into a spice shaker. I use this for nutritional yeast on my popcorn.