Bottle Mockup Creator
I just rediscovered smartmockups.com because they not only do book covers and t-shirts, they also provide quick, free mockups for bottles, supplement bottles, wine bottles... soda cans, smartphones, mugs, laptops, art frames, billboards, you name it.
smartmockups.com/mockups is a user-friendly tool that quickly creates mockups of pretty much anything you can think of. I love it's simplicity, ease of use and quick customizability (like changing a bottle to black, for example). Here are some screenshots of their mockups available: