In no particular order (and apart from the items already mentioned, which are all great) (and, no, I haven't tried everything I'm about to mention... but I'd sure like to try!):
If you're power rated, try gliders.
If you're glider rated, try power.
If you have either, try motorgliders, or microlights.
Fly at night.
Try floatplanes.
If you have lots and lots of money to spare, try helicopters, twins or turbines, or get an IFR rating.
If you're not happy with one outfit (club, school, partnership), try another.
And never forget to tell everyone how much you enjoy flying!
That, and wear sunscreen.
