Many of these replies seem to come from a point of view that optimization and roleplaying can't exist together in the same person. "Optimization" is not a bad word. A roleplayer will do the best with what he's got just like an optimizer that doesn't have a good roleplaying bone in his body.
Where I find distaste is the optimizer that demands high stats--won't play without them. If he rolls low hit points or doesn't have a stat above 11, then he wants to get special dispensation from the DM to re-roll or otherwise demand that he be allowed to "try again" (supposedly until he gets something acceptible to him).
If you're going to do that, then why not just use a point buy system? Why random roll at all?
If you're going to random roll, then accept the consquences. Optimize what you get, and roleplay the heck out of that characters.
Those are the types of players I respect--not the whiners who have to have at least one stat at 18+ and all the others with bonuses.
I've got a character in my current group right now the stretches to the two high-low extremes with his stats:
Caelis Redbirth
STR 19
DEX 13
CON 10
INT 12
WIS 7
CHA 6
He's a first level character; a heck of an athelete (+10 Climb, +8 Jump, +4 Swim); the new apprentice to his family's forge (+6 Craft (Weaponsmith)); and a pretty good clan scout (+7 Hide, +7 Move Silent, +4 Spot, +3 Knowledge (local)).
But, this guy is also very plain spoken. He rubs people the wrong way. He's smarter than the average clansman but is lacking in the common sense department. He's the type that, if you don't like what he has to say, well, he'll invite you oustide and beat you until you agree that he was "right".
You don't want this guy representing the clan when there is a council with other clan chieftains: -6 Diplomacy; -5 Bluff; -4 Intimidate. Even though he's big, at 6', 180 lbs., people tend to underestimate him when he opens his mouth.
This here is a character that is extremely weak in some areas but has been optimized by a roleplayer to "fit" a personality. Did this player wish he'd rolled better stats? You bet. But, he was able to optimize what he did roll (a 17, put into STR, then received a +2 racial bonus) and turn this list of stats into a real character--someone you'd want at your back when on the battlefield but not when you're negotiating a truce.
This jumble of stats now has a real personality.