Turns out? Dragons aren't really dragons.
Well, they are now, but they started off as Kobolds - every last one of them. The real dragons, they're long gone - back in the days before this land was here, great astral beings, more primal creative forces than creatures... they shaped this land, and its people. Before they departed, they left some small piece of their essence in the rising lizard, and thus the lastborn people of this world, the Kobolds, came into being.
Every Kobold has that spark of the True Divine within him - and with enough training, meditation, and soul-searching, any one of them can find ways to unlock their true spiritual potential. The process takes many, many years- most die before they can achieve true enlightenment. Those lucky few will carry on their teachings in a new form, and will attempt to guide others of their kind onto the path of enlightenment...
...Years? Fuck that noise, I wanna be a DRAGON!
You are Kobolds, servants of The Great Dread Queen Anthraxiis, Black Dragon, Plague of the Southern Lands, and you've just found out that she used to be just like you - 3-foot tall and very easy to kill. You have figured out a way to circumvent the decades-long process of draconic ascension - the same process used by your Mistress, a series of arcane rights using esoteric ingredients and bizarre rituals. Can you and your friends locate all the pieces of the ritual, all the while battling vicious monsters, avoiding the suspicions of your Mistress, trying to avoid the backstabbing machinations of your friends, and worst of all, fighting... adventurers!
Yep, just a wee campaign seed to get my juices running again...
Really easy to run using most any version of D&D, but really, 3/4e are probably best (after all, Kobolds before that were little dogmen, and it won't have the same ring to it!).
Problems to look out for using those systems - Kobolds are weak. Yes, I know that's the point, but really - adjust your encounters, or else allow the players the chance to think their way out of fights more than is suggested, whether it's pure RP or Skill challenges. Also, more with 4e, Kobolds fit the Striker/Rogue builds better than others, but encourage everyone to choose different classes to fill out your roles - possibly, by granting Kobolds "V-shaped" stats - for example,+2 Dexterity, +2 Intelligence or Charisma (Kobolds are all about the Sorcerer class).
Other promising systems would include GURPS (lethal, customisable, gives you a chance to really make it your own), or Risus (fast, funny, and very easy to run).