Where have all the Dragons gone?

[fatclown]

ok, I know after the downfall of anacagalon and morgoth at the war of wrath the dragons fled to the grey mountains. I also know that only 2 were mentioned after that, Scatah the worm, and Smaug in the third age. But why aren't they a more predominant force in LOTR? I get the impression that they were quite numerous up there. Had they been fighting unwritten battles with the dwarves of the iron mountains? Why didn't Sauron call the dragons to his aid if he had almost the same power as Melkor. If they were seperated from Saurons power did they remain after his power was destroyed in the fourth age? Give me your imput