I am not traditionally a case user on my iPhone because I like the thing to be as thin and compact as possible. After dropping my 3GS and breaking the screen and upgrading to the new iPhone 4 with twice the glass to break, I am using a case all the time. If you are looking for a cool case that has functionality built in, iKit has a new offering that may be perfect for you.
The new case is called the iPhone 4 Chrome Flip case and has a little kick stand on the back to prop the iPhone 4 up on a flat surface for more comfortable watching. I like to watch YouTube videos while waiting in front of my kid's school in the afternoon so this case will be perfect for that sort of use. I can prop the iPhone on the dash rather than looking down at the phone.
The case has a metallic chrome finish and comes in silver, pink, and blue colors. The blue is a very pale and pastel color making the only real guy color the chrome one. Each of the cases is $34.95 and they are available right now.