This is my lvl 75 ffb spec. It's more fun for me thant the straight frost spec i was using previously. It definetly does more damage. I'll break down why I took some of the talents I did. Bear in my mind that is spec is for leveling.
http://www.wowhead.com/?talent=oZfVccoMhuVubushhI0sk0h
I took world in flames because for leveling I still want to be able to do AOE when there are a bunch of mobs I have to kill for a quest or I have rested XP I can use.
I took Impact for leveling as well, with the molten shileds talent making molten armor proc on ranged attacks as well this actuall procs often. Add to that the molten armor glyph and it's a no brainer
I never cast scorch while leveling so it's worthless to me. I use fireblast and icelance as my instant cast, and I have the talent that reduces the Fireblast Cooldown.
Remember that flame throwing doesn't affect FFB. Thats why I didn't get it.
FFB will proc frostbite which is why i have the shatter talent.
I have 1 point in blizzard so a chill effect gets added. Blizzard can crit now and it will proc frostbite.
There is a bunch of stuff that will change once I hit 80.