The humble, noble sling. Sure, some games have it. Mostly roleplaying games. They're all doing a horrible and disrespectful job at portraying it. A sling isn't some second-rate weapon. It might not be anything but two lenghts of cord with a cup between them (or, if you're fancy, braided cord all the way), but anyone who tells you that a sling is a toy that can't do real harm is either stupid, ignorant or lying. Sure, it might not look like much, especially if compared to other ranged weapons, but it's a lethal thing. If you don't believe it is, watch any Youtube video of a man practicing his slinging. Did you see that stone he hurled towards his target? No, you didn't, it was too fast. Now imagine that that almost fist-sized stone is speeding towards you at the same speed, that being too goddamn fast. Or imagine that it's instead an oval sling bullet made of lead. The Romans had to develop specialized tongs for pulling sling bullets out of the flesh of the wounded and fallen. A good slinger can easily sling a stone over a football field.
And if the unlucky sod at the receiving end has armor? Doesn't matter if it pierces or not, a huge amount of the energy will still transfer through. The blunt force trauma will still be horrible.
A sling has many advantages over a bow, as well. You can only carry one bow, no matter what some silly inventory system has taught you. A bow is a high-maintenance weapon. You have to protect it from the weather. You can't keep it instantly ready for use for too long (you have to keep your bowstring tucked away for many reasons), and you honestly can carry only one. Then you also have to carry all the ammunition, which requires just as much managing and takes much space as well. And even a slight rain can ruin it, to say nothing of wind ruining a shot. You have one bow, and it's cumbersome and needs to be highly maintained and well kept. And its ammo takes much space. And no matter what media tells you, actually shooting with a serious bow is not some graceful little movement. You have to take a proper stance and really bend the thing. You have to use both hands and most muscles in your whole body, and you certainly aren't going to be very mobile.
Now, what's a sling compared to that? First off, you can easily take ten with you. Use one as a sweatband around your head. Tie three around your waist as a belt. Bundle the others up and put them in a pocket. They won't hinder your mobility in any way, and nobody will even know they're there if you want to hide them. And the ammunition? That's everywhere, just pick up a stone. If you're fancy, you might even carry a pouch of sling bullets, of which you will carry more with much less of a hassle than you could carry arrows. You can use it in any environment, and no amount of rain will ruin it (and I guarantee no regular wind will deviate your stone). You can use your sling one-handed, mobile, with a shield. You can sling more and faster than you could shoot arrows.
Seems to me that the sling would be a much more efficient weapon for the archetypal young and brash hero romping through the countryside with an unlikely bunch of allies, wading through mud, water and what have you. Unless he goes for a sword, of course, in which case having a sling still wouldn't hurt him any.
I'm not suggesting that a sling is the perfect weapon or anything. But I'm saying it gets overlooked and giggled at for no real reason. The bow's certainly not better than it, and the sling's not better than the bow. They both have their upsides and downsides, but the upsides of a sling really are a lot more... up than most think. And thus, the humble sling really does need more love.
Oh, and slinging is a great pasttime.