The Little People are a much-beloved character for myself and my regular opponent and we consider them a valuable addition to any team.
Minx and Jinx's stats are two Red, two Blue, two Green, Yellow Stealth, Yellow Wits and White Throw! Overall this makes them relatively good adventurers. Unfotunately they possess only five Speed, but boast an impressive seven Health!
The defining power of the Little People is their ability to throw rocks, sticks and other assorted detritus at anyone nearby. This translates to a natural Throw Attack which can never be lost or dropped. The attack is three Range, Single Target, one Blue damage and Opfire four! Thus four separate enemy characters can be struck in the same turn, if they were all foolish enough to move that close to Minx and Jinx. One Blue might not seems like much, but against your standard four Health, Red Armor character it can be pretty painful. Remember, too, that with their White Throw the imprisonment of their target is a real possibility! Finally, as mentioned before by Spitfire, the Little People's natural Throw attack is one of the best anti-Ulf attacks out there.
I don't usually go far out of my way to pepper people with Minx and Jinx's missles (unless it's someone who's especially vulnerable or heavily wounded), but as with Rizzik's Flamebursts, it is something you should never forget to use.
More frightening are what Minx and Jinx can do with any good Throw weapons you're able to get them. I've seen them use L-Wave Grenades to cripple Reaver Mark VII.
Speaking of Reaver, he has eight Health, Red Stealth, Yellow Armor and limited self-repair, while Minx and Jinx have seven Health, Yellow Stealth and Red Armor. The survivability comparison between the two, however, isn't even close; the Battered War Machine winds up scrap in a good eighty percent of our games, while Minx and Jinx almost never die. An instructive lesson in the value of stealth over armor.
With their Throw, Health and Stealth Minx and Jinx are a possible choice to take the Throw section of the Field of Honor. Study the opposition carefully before making the choice, but dont' cringe from it if the odds are clearly on your side.
If you can't get M and J usable grenades, the next best option is to get them a nice Pistol. With Green Point they can handle a handgun well, and their Stealth and Life makes them pretty hard to take out. I remember one game where the Little People used their pistol to fatally shoot the rampaging Bladed Terror through the eye!
Given their five Speed, a Mount could be profitably used by Minx and Jinx. Their Yellow Wits also enables them to utilize the really fun pieces of equipment like the Holo Twins, the Dazzling Crown, the Repulsor or Glass Blade! They're a good choice to place a ranged Sentinel, too, since they're unlikely to be gunned down in the process.
Minx and Jinx's last power is to steal a card of their target's choice on a Melee roll of five. They are then dismissed at the end of the Melee phase. Since you have a to roll a specific number and the enemy chooses the card, this isn't reallly something to use for deliberate theft; rather it's a way of escaping from Melee combat, which Minx and Jinx really have no business participating in.