So far we know that dragons color tells there strength.
They can pick up and throw npc's.
They breath weapons are shouts

if you have more information i continue to add it to the list to see how much we really know about dragons the beasts of skyrim

Their color tells what magic they use.

They like talking trash to you in untranslated draconic.

I didn't read the post, but just wanted to say that if you need to write "may contain spoilers" in your title tag, you probably want to think about putting it in the spoiler forum.

What? I thought their color tells how powerful they are. Not magic. Todd himself said that Bronze dragons are weakest and other colors are better than those...

They sleep in dens (though im quite sure you won't find a dragon in a indoor cave, or maybe there is.. And it doesn't fly and just fights you in melee combat)