If you're looking for a good primer to dial down shine and up the staying power of your makeup, I have to add Neostrata Oil Free Matifying Fluid to my happy recommendations for oil-slick skin. (Another good one is Smashbox Photo Finish Light, which has less silicone than the original Photo Finish, so feels better on oily skin.)
Yes, Neostrata Oil Free Matifying Fluid ($30.75) has silicone in it, between one and three per cent, says the company. (Dimethicone appears in most skin creams anyway, and seems not to annoy skin for the most part.) But what really does the shine-off oil-absorbing work is something the brand labels "Microsponge Spheres," microparticles that suck up excess sebum to help skin stay matte for hours. And my goodness, they work just like those padded Sponge Towels guys in that paper towel commercial. *SLURP!* Makes my skin feel clean, fresh and velvety.
You can apply this all over your face or just on your t-zone, then top with mineral powder or liquid foundation.
Available at drugstores.