As I'm looking through my stuff and thinking what tools can I not live without, these come to mind. The We R Memory Keepers Corner Chompers. At first when I saw them I thought "why would I want yet another corner rounder?" but curiosity won out and I bought the 1/4" and 1/2" rounder. I didn't use it that much at first but then I tested it on chipboard and I was hooked. Now I don't even use my regular corner rounder punches anymore I just go straight for my chompers. I use them a lot when making the tags for my mini albums because I can punch several at a time. The other pair is the ticket stub and deco corner which I use just as much.
I'm not being endorsed by any companies mentioned, I'm just sharing my favorite tools and products from personal experience.