The 'Colonel Littleton' company does very good quality leather products; they have sleeves for iPads and iPhones, and bags which protect a MBA. However, they are not cheap, but are beautifully made and very resilient.
Likewise, 'Saddleback', another excellent leather company does produce rugged leather sleeves for computers, and, again, they are not particularly cheap but will offer sturdy protection.
Lastly, the TwelveSouth company makes leather sleeves for all Apple computers, in the form of antique leather books (the BookBook product line); these are lovely and very nicely made.