If you create a task to hold tags related to an item list (such as a grocery list) and name the tags for items you might select for the list, you will have an auto-complete item list.

For example, Create a task to hold tags named: "grapes, mango, yogurt, milk" etc. Then create a new task and in the tag field the grocery items will pop up as auto-complete items as you enter text for the tag field for your new task.

I am using these lists for shopping, and in my profession as a videographer, for items to pack or rent for a shoot.