I have a 15 GB iPod and I purchased an iSkin for it. That is the best $$ I have spent on my iPod to date. Prior to having the iSkin, I had to keep my iPod in my pocket while at the gym. The result was a scuffed screen. I got the iSkin exo2 (this was before the evo was released) and it came with a clip and handstrap. I am not sure why the evo comes without the handstrap because that is my favorite part. The iSkin has saved my iPod from absolute damage (I am rather clumsy).
The very first time you drop your iPod, it is a stomach wrenching exeperience, but the iSkin made it no problem. I dropped it once on the treadmill and it was propelled into the block wall behind me...no problem. NOTE: I started using the hand strap religiously after that and I experienced no more drops on my foolish part. Also, the handstrap is great for looping around the handles on the workout equipment or other things in the car. The worse drop was a complete accident....my purse slipped from my hands and began tumbling downward....I caught it upside down only to realize that my iPod was now hurling downwards (I am rather tall) towards the parking lot. Impact right on the corner and one bounce. NOTHING HAPPENED! Okay, I do not encourage dropping and rough handling, but the iSkin is great for protection your iPod. Also, I find that accidental hits to the buttons and scroll wheel no longer affect it because with the skin on, they are recessed.
The only thing I would recommend is not getting the artic color. It is somewhat clear so it makes the iPod look a fuzzy white. It also attracts fuzz so I wish I had ordered the carbon like a friend of mine did. He ordered the carbon for his iPod mini and love it.