Spyderco Honeybee. This is about the shortest useful blade length, at barely over 1.5". All metal, handy Spyderco opening hole, and perfect for a necklace, or on a keychain with a micro-light.
The Gerber Shard is a lightweight, inexpensive little keychain tool with screwdriver heads and a bottle opener on a pry bar. The screwdrivers may be too fat to use well, but the pry bar and bottle opener alone are well worth the cost. Buy from Amazon for cheaper shipping.
Spyderco Grasshopper. Similar to the Honeybee, but with a blade over 2", the Grasshopper is a super-inexpensive way to give a useful pocket knife to someone, or at less than $9 right now from Cutlery Shoppe, cheap insurance to stash in backpacks, buggout bags, or emergency kits.
I have used and owned many different keychain lights, and the Photon Microlights are the best of the squeeze-activated. The Photon IIs have a choice of squeeze-on or lock-on, so the light can be set down or hung up without turning off. The red is a good choice for finding your way in the dark without destroying your night vision, and has an extremely long battery life (over 120 hours). I have broken many other small lights that you might think are similar, both cheap lights and the more expensive Inovas. I have never broken a Photon. (Note: be careful about ordering the "cheapest" one from Amazon. Some buyers tack on a $5 or more shipping charge per light. Order this one.)
The Spyderco Persistence, Tenacious, and Resilience are Spyderco's new made-in-PRC line. They offer multi-positionable pocket clips for right or left-hand and tip-up or tip-down carry, G10 scales, and skeletonized liners. All with the sterling Spyderco reputation and quality control. I have bought Persistence and Tenacious folders to give to friends, and they are extremely high-quality knives. (I actually prefer the G10 used on these to the G10 used on higher-end Spydercos, because it's not as abrasive and destructive to pants.) Cutlery Shoppe has the best prices I've found for these, ranging from $25-35, and Jeff at Cutlery Shoppe is just a really nice guy.
When it comes to suitability, the Persistence is sized to be a good daily folder. The Tenacious is starting to get into big folder territory, at almost 3.5" of blade, and the Resilience is just huge, with over a 4" blade. It's probably best suited to outdoor uses, Rambo. Rocky National isn't quite as cheap as Cutlery Shoppe, but if you want that extra touch, you can order your blade etched from them for an additional $4.95, and it only adds one day to your order.
Well, what if the person you're buying for doesn't like knives or lights? While it's hard to imagine such a person, should they exist, here are other options.
If your recipient is at least 11, an excellent choice is Orson Scott Card's Ender's Game. This is a simply-written but deeply thought-provoking book about adolescence, life, history, war, and the importance of each individual decision. Oh, it's just a fun read, too, whatever your age. ;-)
If you are buying for a teen or adult who enjoys reading action-packed books, John Ringo's A Hymn Before Battle (Posleen War #1) is the first of a 4-part series that is perhaps the most enjoyable multi-part scifi I have ever read, helping me pass some otherwise dreary hours in a god-forsaken 4th-world hellhole. In fact, if you are trying to encourage a teen to read, giving this book might be the incentive they need to dive into the remainder of the series: Gust Front, When the Devil Dances, and Hell's Faire. And- once they have an appetite for reading- they aren't likely to stop there.
Not as refined, but just plain fun, my buddy Larry Correia's Monster Hunter International was the first book in years to keep me awake until I finished reading it. If you've read the first, the sequel, Monster Hunter Vendetta is now out.
Alec Baldwin was in at least one good movie, and it's rare enough that your intended has almost certainly never seen it. And this movie is good enough to make up for the rest of Alec Baldwin's career before 30 Rock, filled with intelligent but understated humor and precise but not pretentious dialog.
Mel Gibson's an ass, but for war movies, it's hard to beat the real-life-based We Were Soldiers.
If you want to give music, Diana Krall's When I Look in Your Eyes is an all-time favorite of mine, and music that almost any adult should greatly enjoy. If your person doesn't enjoy classically great music, try Taio Cruz's Rokstarr. (Note: not claiming this is "good" or "good for teens", just that they'll almost certainly enjoy it. You may, too, but you don't have to admit it.)
For the refined of taste but reading and listening impaired, consider some delicious Lazzaroni Amaretti di Saronno Italian cookies. Packed in a colorful tin, these amaretto cookies are simply the best in the world. Yeah.
Okay, so the person on your list reads, but doesn't enjoy purely fun books, or just wants some intellectual stimulation. Too easy.
Friend Gary Yee's Sharpshooters is both readable and exhaustively researched. Not cheap, but highly recommended, and packed so full that it's like getting three solid books in one.
Mentor Mark Fissel's The Bishops' Wars: Charles I's Campaigns against Scotland, 1638-1640 is at the pricey end of the book spectrum, but sure to impress. And Dr. Fissel is worth reading.
Okay: what if none of these things seems to be what you've looking for? Hell, I dunno. Get 'em a slingshot. And eye pro, kids.