Include sliders that allow the user to set both the intensity and speed of the effects.
Even the mildest effects were too intense for me to leave running while I work, but a lighter, slower version that I could customize to suit my mood would be great.
With Sliders, you could also cut the number of variation types (rain, wave, etc.) down to two or three. As it is, having so many options that are essentially the same thing is a little overwhelming.