Here are my SASS mixins i am currently using. Maybe someone can use them:

/**
 * CSS3 Border-Radius
 *
 * @param $topLeft Either the top left radius, if no other param provided, this value is applied for all params
 * @param $topRight [optional]
 * @param $bottomRight [optional]
 * @param $bottomLeft [optional]
 */
@mixin border-radius($topLeft, $topRight : null, $bottomRight : null, $bottomLeft : null) {
	@if $topRight == null and $bottomRight == null and $bottomLeft == null {
		$topRight : $topLeft;
		$bottomRight : $topLeft;
		$bottomLeft: $topLeft;
	} @else if $bottomRight == null and $bottomLeft == null {
		$bottomRight : 0;
		$bottomLeft : 0;
	} @else if $bottomLeft == null {
		$bottomLeft : 0;
	}
	-moz-border-radius-topleft: $topLeft;
	-moz-border-radius-topright: $topRight;
	-moz-border-radius-bottomright: $bottomRight;
	-moz-border-radius-bottomleft: $bottomLeft;
	-webkit-border-radius: $topLeft $topRight $bottomRight $bottomLeft;
	border-radius: $topLeft $topRight $bottomRight $bottomLeft;
}

/**
 * CSS3 Box-Shadow
 *
 * @param $inset Either true or false
 * @param $x
 * @param $y
 * @param $blur
 * @param $spread
 * @param $color
 */
@mixin box-shadow($inset, $x, $y, $blur, $spread, $color) {
	@if $inset == true {
		$inset : inset;
	} @else {
		$inset :"";
	}
	-webkit-box-shadow: #{$inset} $x $y $blur $spread $color;
	-moz-box-shadow: #{$inset} $x $y $blur $spread $color;
	box-shadow: #{$inset} $x $y $blur $spread $color;
}

/**
 * CSS3 Text-Shadow
 * @param $x
 * @param $y
 * @param $blur
 * @param $color
 */
@mixin text-shadow($x, $y, $blur, $color) {
	text-shadow: $x $y $blur $color;
	filter: dropshadow(color=#{$color}, offx=#{$x}, offy=#{$y});
}

/**
 * CSS3 Multi-Column Layout
 * @param $columns
 * @param $gap
 */
@mixin columns($columns, $gap) {
	-moz-column-count: $columns;
	-moz-column-gap: $gap;
	-webkit-column-count: $columns;
	-webkit-column-gap: $gap;
	column-count: $columns;
	column-gap: $gap;
}

/**
 * CSS3 Outline
 * @param $thickness
 * @param $style
 * @param $color
 * @param $offset [optional]
 */
@mixin outline($thickness, $style, $color, $offset : null) {
	outline: $thickness $style $color;
	@if $offset != null {
		outline-offset: $offset; /*Delete if you don't want an offset*/
	}
}

/**
 * CSS3 Transition
 * @param $property
 * @param $duration
 * @param $function [optional]
 */
@mixin transition($property, $duration, $function : ease) {
	-webkit-transition: $property $duration $function;
	-moz-transition: $property $duration $function;
	-o-transition: $property $duration $function;
	transition: $property $duration $function;
}

/**
 * CSS3 Transformation
 * @param $scale
 * @param $rotate
 * @param $translate
 * @param $skew
 */
@mixin transform($scale, $rotate, $translateX, $translateY, $skewX, $skewY) {
	-moz-transform: scale($scale) rotate($rotate) translate($translateX, $translateY) skew($skewX, $skewY);
	-webkit-transform: scale($scale) rotate($rotate) translate($translateX, $translateY) skew($skewX, $skewY);
	-o-transform: scale($scale) rotate($rotate) translate($translateX, $translateY) skew($skewX, $skewY);
	-ms-transform: scale($scale) rotate($rotate) translate($translateX, $translateY) skew($skewX, $skewY);
	transform: scale($scale) rotate($rotate) translate($translateX, $translateY) skew($skewX, $skewY);
}

/**
 * CSS3 Background Gradient
 * @param $color1
 * @param $color2
 */
@mixin gradient($color1, $color2) {
	background: -moz-linear-gradient(top, $color1 0%, $color2 100%); /* FF3.6+ */
	background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,$color1), color-stop(100%,$color2)); /* Chrome,Safari4+ */
	background: -webkit-linear-gradient(top, $color1 0%,$color2 100%); /* Chrome10+,Safari5.1+ */
	background: -o-linear-gradient(top, $color1 0%,$color2 100%); /* Opera 11.10+ */
	background: -ms-linear-gradient(top, $color1 0%,$color2 100%); /* IE10+ */
	background: linear-gradient(top, $color1 0%,$color2 100%); /* W3C */
	filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#{$color1}', endColorstr='#{$color2}',GradientType=0 ); /* IE6-9 */
}