Rip Tweezers is my all time favorite ripping tool. I thought it pricey the first time I bought them, but OMG....they are so worth the $10.00. I prefer a ripper with a small end that will squeeze into small stitches. Hobby Lobby has these for a couple of dollars. They are the same that come in the Brother and Babylock machines. The Rip Tweezer has this smaller blade with the tweezers attached. The first time I needed to turn the ripper around and use the tweezers to pull out a piece of thread that I couldn't get with my fingernails, I was hooked.
http://www.riptweezer.com/