I was looking at some lamp parts on a website and I noticed in their bulb section they carry "silver crown bulbs". What are silver crown bulbs and why would you use them?

I aasme these are the lamps with the silvered reflectors on the top of the envelope (the end away from the lampholder). They are used when you want indirect light from the luminaire. (mounted base up)

I put one in a table lamp that was on a short nightstand. That way I saw the silver coating instead of the bare filament.
A lot easier on the eyes if you had to turn on the light and go...get a drink of water.

used a lot for dressing mirrors, did some work in a theater, they had them at all the make-up tables

I see them in resturants where they have pendants over the table. It dresses up a lightbulb on a cord and softens the light