Gregory's Server
naturally the topic gets even more complex when you add in ESD protection.
some folks mentioned adding a "bleeder" resistor in parallel with the coupling capacitor. i'm leery of adding series impedance to limit the current, typically you want that ESD out of there without giving it opportunities to current share with sensitive signal returns. also it turns out that many resistors can get destroyed by an ESD pulse, so there's another good reason to avoid this approach.
you might be OK if you add a shield ground ring around the board, near any gaps in your enclosure, so that ESD strikes will hit that rather than your main board ground. you should also protect any buttons or switches. for example, some tact switches come with a shield ground ring that goes to a 5th pin, which should be tied to your shield ground.