Some items I have heard of security not allowing on planes: nailfiles and fingernail trimmers, disposable razors, a brooch with a 1 1/5 inch pin on the back, _plastic_ knives, and anything else that could be construed as 'sharp'.
I personally shy away from discussing what I do or might carry for personal protection, so it can't be quoted for 'intent' purposes, but from the side of me that worked camp maintenance for a number of years, I carry a flat-rolled pack of duct-tape, and plan on acquiring the first plier/screwdriver/keychain thing I can find for less than 10 bucks that has nothing resembling a cutting implement on it. I also always have a flashlight or two on me/in my bag(carry-on). After a multi-day power outage that gave me a little mroe respect for electricity, I've upped the size of the light in my bag. And, lastly, for my own enjoyment, I own a couple bamboo flutes, of the solid, take-camping-with-you variety, in alto scales (my personal favorite is an E flat) and frequently one of those is in my bag.
My biggest beef about the current security status, is that if I desired to, I could bring a very effective combat knife on board with me, I would just have to have it made out of something non-magnetic. Shoot, my understanding of the security systems leads me to believe the Titanium stage swords made for theatre would pass right through the metal detectors, and cut nicely through a person if sharpened a bit. But, since I prefer to stay on the legal side of the world, I am not allowed to carry the pocketknife or belt tool that I walked around society with for years. I don't have a solution to make both sides happy, but my side ain't happy.
Stryver