Kind of off topic, but since it kind of came up....
I remember reading not too long ago of an optional rule that Monte Cook wrote about. Normally, a spellcaster selects an intersection of grid lines on the battlemant to be the center point of his spell. The optional rule is for the spellcaster to pick a square instead of a line intersection, and then roll 1d4 to randomly determine which corner of the chosen square is actually the center of the spell effect. That way, the range (and area) of area spells has a chance to be off by 5 ft.
For some this adds a little realism in that most people cannot pinpoint exact distances. For me, though, it's another dice roll to slow down the game.
As for the occassional realists in my game who ask how anyone can be so precise, I give the same answer whenever reality tries to intrude on my game: "It's magic."
Later,
Atavar
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"Love is not a vict'ry march, it's a cold and it's a broken Hellelujah." - Hallelujah