As an avid quilter and Morsbagger I wouldn't be without my 23" x 17" cutting mat and 23" x 6.5"clear plastic ruler. They're the perfect size for cutting fabric straight from the bolt ie. 44" wide (which is how most fabric comes).
I've an Olfa cutter which closes when you put it down, which is great.
I can cut through several layers of fabric no probs (especially with a new blade

)
You can also get big handles which attach to the rulers by suction and are great for anyone with arthritis or carple tunnel problems. It really helps to hold the fabric down firmly.
You can get them from any quilting shop or online.
(I've tried cheaper cutting mats but I found they didn't last too well.)
I've had my good mat and ruler at least 10 well-used years.
