Handy little snippet for generating block shadows with SASS.

block-shadow.sass

=vendor($property, $value)
	-webkit-#{$property}: $value
	-moz-#{$property}: $value
	-o-#{$property}: $value
	#{$property}: $value


=block-shadow($distance, $horizontal, $vertical, $color)
	$property: null
	$i: 1

	@while $i <= $distance
		
		@if $horizontal == left and $vertical == bottom
			$property: $property , -#{$i}px #{$i}px $color

		@else if $horizontal == left and $vertical == top
			$property: $property , -#{$i}px -#{$i}px $color

		@else if $horizontal == right and $vertical == bottom
			$property: $property , #{$i}px #{$i}px $color

		@else if $horizontal == right and $vertical == top
			$property: $property , #{$i}px -#{$i}px $color
		
		$i: $i + 1

	+vendor(box-shadow, $property)

.box
	+block-shadow(5px, left, bottom, #ddd)

box-shadow.css

.box {
	-webkit-box-shadow: -1px 1px #dddddd, -2px 2px #dddddd, -3px 3px #dddddd, -4px 4px #dddddd, -5px 5px #dddddd;
	-moz-box-shadow: -1px 1px #dddddd, -2px 2px #dddddd, -3px 3px #dddddd, -4px 4px #dddddd, -5px 5px #dddddd;
	-o-box-shadow: -1px 1px #dddddd, -2px 2px #dddddd, -3px 3px #dddddd, -4px 4px #dddddd, -5px 5px #dddddd;
	box-shadow: -1px 1px #dddddd, -2px 2px #dddddd, -3px 3px #dddddd, -4px 4px #dddddd, -5px 5px #dddddd;
}

Changed three of the if statements to else if statements for better performance.