On my last trip to London, I picked up a boxed MobileMe activation key at the Regent Street Apple store. On account of Sterling dropping like a stone, this works out substanially cheaper than renewing online in the local currency, and it actually works! Although I'll say that Apple doesn't exactly go out of its way to make it easy - the option is absent from inside your MM account. You have to use this link - which I obtained from MM support via a pleasant online chat. It was the first time I actually used that support feature, and it worked really well, so thanks for that!