No parking should be "free", ever. All parking arrangements should be handled either as private property or as rental/lease agreements on a short-term basis. Meters are a fine way to administrate short-term parking, and new credit-card based technologies will make it even easier.
I would argue that all currently "free" parking spaces owned by the city/state should be put up for auction, with an exclusive first option to buy going to the owner of the nearest adjacent property (I'm guessing $3-5k initial price for urban spots, less for suburban). Installment plans could be made available to those owners who cannot afford the upfront cost. Public parking arrangements could be made by placing normal city meters at the same spots, on a revenue sharing arrangement between the city and the owner of the spot. The city would manage the coin collection (or credit card system), plowing, and towing services for a cut of the revenue, while the owner of the spot could generate some income if/when they were not using the spot themselves. The city's end of the service could easily be privatized or liberalized entirely, but that is inessential to the function of the system I am proposing. Spot owners could set the terms for the fees/times/availability of the spot, within some basic guidelines (e.g. no sudden fee/schedule changes, no capricious towing without warning, etc.)
And if anyone wants to help make it economically feasible to build mass-transport options between nearby cities like Madison-Milwaukee, one of the first things you should advocate is the end of "free" parking.