Most laptop bags, cases, and sleeves aim for a studied anonymity; they're cast in basic black nylon that looks as fitting in a corporate boardroom as it does in a college dorm. Those looking to break out of that generic rut should check out the line of laptop sleeves from ColcaSac, made of materials such as hemp and burlap, and lined with fleece. This $33 13-inch version, made of dark brown hemp canvas, is a bit pricey for a laptop sleeve, but is well-constructed, and is flexible enough to hold several kinds of laptops, even if it's specifically marketed at MacBook owners.
Measuring 14 inches tall by 9.75 inches wide with the top flap folded down, the sleeve is a surprisingly tight fit for the current 13-inch MacBook, but perhaps the natural fibers will stretch a bit with time. Other 13-inch laptops fit with no problem, and for larger laptops, the company makes 15-inch and 17-inch versions, as well as smaller sleeves for 12-inch PowerBooks (which might be good for Netbooks as well).