I've got a few more things to add to my list:
Spend the night in a tree-house (I had a link for this somewhere...).
Listen to all of Maggie Mason's song links from her 1,000 song project.
Attend a Cardinal baseball game in every National league stadium, and a game in the American League stadiums.
Witness a flash-mob, live and in-person.
Try acupuncture for migraines/cluster headaches, and stress reduction.