Have you ever been crafting and had suddenly forgotten how to create something? Do you really want to go to Minecraft Wiki and look for what you want to make? Well, a list of recipes would help.
By pressing a button, you could view a list of recipes, click on one, see the required materials and if you already have them in your pockets. So, if you are crafting a Redstone Repeater, you would press 'G' and it opens a menu. You click the name "Redstone Repeater" and it opens a crafting box with the items needed and in their positions. It would also have a check or an 'X' to show if you have the materials. I do not think this next detail is totally necessary, but if you do have the required materials, you could press a "Craft Now" button to save the time it takes to craft those ladders.
I have often thought about this and believe that it would be a useful addition to Minecraft. Thank you!