I just picked up a pair of Howard Leight Impact Sport muffs and I'm very happy with them.
+1
I have had three other kinds of electronic muffs including Peltors and so far these are my favorites. Having the auto shut off is a a real plus because I was always forgot to turn my off at the end of the day and had dead muffs at my next trip to the range. Another nice thing about these is that they come with a hookup for your walkman type device so that you can listen to your favorite music if you like while you are shooting at the range. That's kind of cool I think.
Oh, and Cablelas has them on sale for $50 too. Good deal made even better.