As a DM, how would you deal with a sorcerer who can one-shot anything of his CR once to several times per day with metamagicked fireball?
throw things with resist fire? throw bigger things? throw more things? just let him nova and try to wear him down with multiple encounters? just let him be awesome?
I'd do exactly what my DM did with me. Talk with the player, and ask him not to steal too much of the spotlight, and allow other players to do their thing and be awesome too. My character has only a few blasting spells (fireball, scorching ray, and dragon breath). I also have Haste, Dispel magic, Improved invisibility for the party rogue, Dimensional door to move people around...
In some encouters, I totally dominated (specially when facing big mobs of creatures below CR, obviously). In some others, I couldn't do jack (I remember being Feebleminded in a fight vs a black dragon in turn 1, for example). Most the time, I mixed haste, Enlarge person, fly, and other stuff before going wild in fire, or I casted a fireball to clean most of the "mooks" and then buff my party so they have an easier time with "tank and spank the boss".
On a side note, there are a lot of situations where you can't simply go wild with the fireballs. There are allies in the area, there aren't that much targets nearby, you don't want to burn the furniture, you are surprised and surrounded, the monster is fire inmune (fire resistance isn't really an issue most the time, if you do 90+dmg, having FR 10 won't help that much), you are fighting in a small room... That's where, Imho, a blaster sorcerer beat a blaster wizard. As a wizard, you have memorized a lot of fireballs (or whatever is your blasting spell of choice), and when you can't use them, you are hosed. A sorcerer simply start to spam any other spell (haste, dispel magic, slow, fly, whatever) and be happy with it.