Super Dry Chalk
This chalk has a drying agent in it, so it's great for people who tend to sweat a lot, like me. I'm addicted to this stuff, and feel like I'm slipping off holds if I use regular block chalk now. My best friend has very dry skin, and she doesn't like this chalk because it actually makes her hands too dry (hard for me to relate to). So if you grease off holds a lot, don't have dry skin and/or live in a humid climate, you will probably notice good results with this.