The San Francisco Chronicle recently got confirmation from TSA officials that there are more items specifically allowed in carry-on luggage than you might expect. Among them are whips, chains, handcuffs, vibrators, and other personal "toys" that don't exceed certain measurements—in other words, they're OK to go as long they don't become "club-like."
On a slightly more practical note, traditional lighters are allowed too. TSA agents will still confiscate torch lighters, but they'll leave your standard Bic or Zippo alone—you can even keep it right in your pocket after you get through screening.
Mothers can also now take a "reasonable" supply of breast milk or baby formula with them on flights whether their children are with them or not, but they have to hand over the goods to be treated as "liquid medication." Whether that means an agent will dip test strips in it or just eyeball the bottles is something that would probably depend on how bored they are at your checkpoint. Photo by Brett Lider.
Update: Several commenters point out that the "liquid medication" provision has also allowed them to bring larger bottles of contact solution—a handy tip for those of us who would rather not buy a travel size every time we fly.
If you pack a vibrator, don't get shaken by TSA | San Francisco Chronicle via Gadling