This was assuming you're holding onto the wallet.dat as a long term value storage option - print out the wallet, mark down the addresses, and delete the original file. Then store someplace safe 
Easy to deposit coins to the wallet, but hard to withdraw.
Easy to deposit coins to the wallet, but hard to withdraw.Or, for that matter, burn the thing onto a CD, place the disk in a safety deposit box, and delete the original.
If there's enough demand, a 2-d barcode format suitable for printing a wallet and rapidly scanning it back in can and will be developed. That way, you can have the relative permanence of paper, and the ease of digital data.