This is probably widely known by everyone (including extraterrestrials) but it's something I just figured out today. It's probably pretty sad considering I'm a KGS 7 Kyu. But observe:
$$Dia. A
$$------------------
$$|. . . . . . . .
$$|X X . . . . . .
$$|O O X . . . . .
$$|C X O . . . . .
$$|. O . . . . . .
$$|. . . . . . . .
$$|
$$|
- Click Here To Show Diagram Code
[go]$$Dia. A
$$------------------
$$|. . . . . . . .
$$|X X . . . . . .
$$|O O X . . . . .
$$|C X O . . . . .
$$|. O . . . . . .
$$|. . . . . . . .
$$|
$$|[/go]
The space marked with a circle is where we common play (at least I do) and it's what is generally perceived to be correct (to me), but it's not the best possible move. Observe:
$$Dia. B
$$------------------
$$|. . . . . . . .
$$|X X . . . . . .
$$|O O X . . . . .
$$|. X O . . . . .
$$|C O . . . . . .
$$|. . . . . . . .
$$|
$$|
- Click Here To Show Diagram Code
[go]$$Dia. B
$$------------------
$$|. . . . . . . .
$$|X X . . . . . .
$$|O O X . . . . .
$$|. X O . . . . .
$$|C O . . . . . .
$$|. . . . . . . .
$$|
$$|[/go]
This play results in a snapback, if white captures, which seems to be better in my opinion. Either way the result seems to be a tiny bit better by at least a point. Sorry if I'm pointing out the obvious (or if this has been pointed out before) but I thought it might at least benefit someone. If I'm incorrect, feel free to correct me.

Edit: In both diagrams, it's

's move.