Y'know.. you *could* always just work out a budget with the wife....
it's what i have going with my GF (no, we don't live together, but we tend to take trips together)
basically, what i have going, is there's a certain amount that we both contribute to a joint account for vacationing/spending; this is a monthly contribution. when we go someplace, there's a certain amount of spending money alotted, broken down into thirds, one third is mine, one third is hers, and one third is for gifts or if we find something really unique.
same could be done for you and your wife... work out a certain ammount a month each of you get for hobbies and the like and an 'overdraft' that you have to have the other's permission to spend.
hmm... you whores actually have me considering how to get my hands on a set of emag lowers... damn you.