I'm not normally one for fancy aesthetic mods for laptop covers, but I can't help but love Paul Smith's Syncopated Stripe wool laptop cover. It's flat-out awesome.
At $US45, it seems totally worth the price for someone looking to add a bit of flair to their laptop. Unfortunately, most of the Macbook sizes are sold out, but the PC sizes are still in stock, so hop on it while you can if you're interested. [I Am Human Now via Book of Joe]