I'll mention again that an old mat is perfect to use to pink the raw edges of fabric before pre-washing. Rotary pinking blades are wonderfully quick to use but they tear up mats something awful!
FYI, I use a long carpenters rule to cut along. Not my precious quilting rulers!
I just bought a huge Martelli mat at their half-price sale. That was a big investment for me, so it better last a really long time!
So far I love it and their ergonomic rotary cutter is a keeper!