Dampits are probably the way to go with what's available now. If you haven't seen them before, Bob Taylor offers some great videos on their website about humidifying. These show the restoration of a severely dehydrated/damaged guitar:
http://www.taylorguitars.com/see-hea...t.aspx?id=1004
There are three videos on humidity. One that shows the effects, another that shows restoring a dry guitar, and another where they intentionally dry one out in a humidity chamber. Very interesting.
Edit: Well, that link doesn't take you there directly. There's a menu on the right side and the humidity videos can be found under the Performance/Maintenance Tips tab of that menu.
Jim