hi, another mostly lurker here.
My husband and i get $20 a month each. We have a budget w/ ab 12 categories, we do the envelopes of cash for things like gas, healthcare (co-pays, meds). tithe, groceries and fun, and pay our bills out of the first of two monthly checks and deposit the second into savings.
As for our fun$$ for each of us- our son is just 1, so we don't give him cash yet- my husband actually gets $5 cash and plays WOW several eves a week after our son goes to bed (that costs about 15 dollars a month) and i may go to the thrift store, order a book (very small towns don't have expansive libraries and ours charges by the day for interlibrary loans, i can buy books used online for less then that), buy gifts for friends (not in the reg gift budget- that is for family), get something like cookies at the farmer's market or save it. We don't have an eating out budget- but very very very very occasionally we will use our own spending money to take each other on a date- usually when we are on vacation or take a trip to the city.
For me, having a little wiggle to spend on whatever helps me not feel deprived and keeps me from spending what i shouldn't. Occassionally, we might not put anything in our envelopes if its a tight month, or we are close to a spending goal and want to put aside some extra, but for us, its better to not do that too often.