I'm surprised only one person (?!) mentioned any kind of "yours, mine, and ours" technique. If you and your spouse both bring in income, I highly recommend it. Basically, each time we get paid a chunk of money goes into "our" account, which is used for mortgage, other bills, retirement savings, etc. Then what's left from our paychecks after the predetermined chunk goes to individual checking accounts. This money is ours to use free and clear. We can do what we want without any comments from the other person (within reason, obviously 6 ft electrostats in the living room would be a problem for a different reason).
We haven't been married very long, but this seems like the best approach. Everyone values some things more than others (I would never want as many shoes as my wife, but she would never understand why I would replace a perfectly good CD player with something very similar), and this way there's no guilt or begging or anything. Obviously for truly high ticket items, it might take awhile to save up enough, but with all the credit problems and economic problems, I'm not sure that's so bad.
-Eric