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I don't have one for a Macbook since I don't have a Macbook but I do have an iSkin for my iBook and another for my iMac and they are great.

I wouldn't get it from ebay though, especially that particular one since that iSkin is for iBooks and Powerbooks (I believe that is an old Powerbook in the picture).

If you want to check out the ones made for the Macbooks head over to www.iskin.com
 
I have an iskin for my powerbook, i highly recommend them. Except you do have to do some washing of the skin sometimes after some use. Easiest way to get them is to go to the apple store, they are always there.
 
I don't have a Macbook yet (soon though) but my friend has the iSkin and highly recommends it. I plan on getting it as well.
 
Isn't there an issue with some heat escaping (on purpose) through the keyboard? Wouldn't covering the keyboard present a heat issue?
 
I purchased an iSkin (Amazon) about 2 weeks after I bought my MacBook C2D. I don't know why I waited. The cover works very well. The feel of the keyboard is still there. I will need to wash it soon (the instructions in the book say how (soap & water)). I don't really notice a heat change, then again, the MacBook isn't very hot...warm, but not hot. Glad I purchased one.
 
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