Mathematica 6 lets you immediately introduce any number of controls.
In[1]:=  |  Manipulate[
Graphics[{Opacity[.75, Red],
Table[Disk[Sqrt[i] {Sin[i (a Degree)], Cos[i (a Degree)]},
size], {i, 0, n}]}, PlotRange -> Sqrt[n] + size ],
{{n, 100, "number of disks"}, 1, 300},
{{size, .75, "radius of disks"}, 0.1, 2},
{{a, 137.5, "angle"}, 0, 180, Appearance -> "Labeled"}] |
Out[1]=  |