SOG make excellent knives: I know because I had many of them confiscated by the nascent TSA in the early days of the Global War on Terror, that liminal moment when I was still kidding myself that I would remember to empty my pockets of useful tools before boarding a flight.
Since then, I have pieced together a set of backpack tools (a cheap no-name multidriver with some extra bits) and put Widgy's smallest prybar on my keychain (this has evaded airport confiscation for five years, in literally dozens of countries — and it's got enough of an edge on it to open parcels and difficult packaging, as well as serving as a useful prybar).
But every now and again, I like to play alternate universe and imagine what I would carry if I could either trust myself to reliably put everything confiscatable in checked bag, or if the TSA decided to abandon security theater in favor of real security, and this SOG Key Folding Knife KEY-101 is exactly the sort of thing I would put on my keyring, in a heartbeat, if I didn't have to worry about flushing $10 down the toilet the next time I fly.
It folds neatly and perfectly into a replica housekey, has over 2000 positive reviews, locks open, and comes from SOG, who, as I say, make some damned good knives. Many of the commenters report having successfully taken it through TSA checkpoints, and if you want to buy in bulk, there's His n Hers pink and blue versions at $15/pair (there's also a $9 stealth version that has the same coloration as a default housekey).