Is it possible to use Bitcoin client without
wallet.dat file, by entering your addresses and being able to see the balance, but without the ability to spend bitcoins? I know that it's possible to backup
wallet.dat and use another
wallet.dat, but in that way you don't see your transactions and balance and can't label your addresses etc.
If it's not possible in official client (I believe it isn't), are there alternate clients that allow this? The point is to be able to backup
wallet.dat and plug it in only when spending bitcoins, but not lose the ability to see your transactions in the meantime.