Apologies if this is well-known, but I just figured it out! If you enter the main photo in your listing in an Image Search on Google, you can get a list of the "Popular on Etsy" pages that your item has shown up for. For example, I see my listing for expected phrases like "custom album" and "wedding photo book", but I never considered "layflat" as a particular term for my items!
If you'd like to see this example, my test URL is pretty long, so here is a bitly:
http://bit.ly/136wz4K
