There is a new Mac app called SpriteRight for doing CSS sprites that is pretty darn nice. I'm a fan of both SpriteCow (beautiful interface, design your own sprite) and SpriteMe (automatic combining of sprites, gives you real CSS). I feel like SpriteRight hits the nail on the head by combining the best features of both of these tools, doing it better, and doing more.
Here's their intro video:
It's normally $9.99, on sale for $4.99, but if you want to get it for free, I have some codes you can redeem in the Mac App Store. I will send the first five folks who record an audio question for ShopTalk and send it in. Doesn't even have to be a question, could just be a topic or hot tip you'd like to hear us talk about on the show.