Being a faux painter in Atlanta, I use a lot of gold metallic paint.  Gold metallic is very popular for trim and accents, as well as being worked into wall designs and for stenciling.

I have tried many brands of metallic paint.  Some are better than others.

Benjamin Moore Precious Metals: Nice selection of colors, but it is an opaque products requiring at least 2 coats. Area must be primed and sanded before application. Latex based, soap and water clean up

Behr Luminoso Thicker product, but requires a sanded primed surface for best results. Water based for easy clean up. Can be sprayed, but can only be thinned with 2 oz per quart or less. Requires at least 2 coats for best results

Modern Masters. Great product-good coverage-water based for easy clean up

Faux Effects Ducth Metals  By far the best product I have used .  This brand comes in silver, copper, brass, and gold.  It is water based, for easy clean up, and can be mixed into glazes and added to other colors with ease. This product can also be thinned with water and sprayed.

Here are two examples of gold painted trim.

This trim and door inserts were painted first with Behr satin finish yellow, then 2 coats of Behr Luminoso. 

This trim was painted with one coat of Dutch Metal Gold over high gloss white.  This paint works well over any surface, and if prepped properly, even metal itself!

In my opinion, the Faux Effects product gives exceptional adhearance and coverage. none of the other products could cover this well over high gloss white in one coat.

I'm sure there are other  paints out there, and with the trend going towards the metallic looks, I'm sure other products will pop up in the near future.

Keep your eyes open for more metallics!