When farming Terramorphous last night we found that he exclusively dropped orange Class Mods with nearly identical effects (he dropped other loot, but the orange loot was always a single mod, every time). All of these had +4 to 6 different skills, and +20% to 25% Burn damage and Burn Effect Chance, and + some amount of max health.
These mods are really fairly useless, aside from the skill bonus. They're okay for Siren (still sub-par burn %s however) but do they really only drop Burn Damage or did we get an unlucky batch? I saw Gunzerker, Assassin and Siren mods. The 2 Siren mods were identical, and the non-siren mods all had the burn chance and health bonuses.