One of my work mates had some code with a lot of floating point clamps in it the other day so I wrote this little branch free version using the PS3's floating point select intrinsic:

float Clamp(float x, float lower, float upper)
{
    float t = __fsels(x-lower, x, lower);
    return __fsels(t-upper, upper, t);
}

__fsels basically does this:

float __fsels(float x, float a, float b)
{
    return (x >= 0.0f) ? a : b
}

I measured it to be 8% faster than a standard implementation, not a whole lot but quite fun to write. The SPUs have quite general selection functionality which is more useful, some stuff about it here:

http://realtimecollisiondetection.net/blog/?p=90

(Not sure about this free Wordpress code formatting, I may have to move it to my own host soon)