What is best delivery medium for topical herbs?

I want to make a topical with some herbal ingredients but I don't know what the best delivery medium would be. Obviously it will need to have a low molecular weight so it can pass through the skin rapidly. I'm not sure oils actually pass the skin as triglyceride's are large molecules. Perhaps free fatty acids would be an option. Study have shown coconut oil will penetrate the skin as will jojoba oil. The problem with oils is you can only use them at night (unless you want to walk around with a grease head). Oil also causes your hair strands to clump together making your hair loss even more viable!
Alcohol has been used since ancient times but probably not that good for your scalp.
DMSO is probably one of the best but there is debate as to the safety of using this long term.
Emu oil is advertised as the most penetrating oil but a quick look at its make-up reveals that olive oil should be just as good and cheaper.

So whats your thoughts, what have you used as a delivery medium for your topicals?

I strongly believe that any product from Dr. Bronners Magic Soaps is the best topical out-there. It lathers very well with little soap and is very cost effective. The products are 100% organic and contain oils like jojoba-oil, hemp-oil, coconut-oil, olive-oil and vitamin-E in every product. My personal favorite so far is the peppermint-oil, thou I have only tried one other; tea-tree-oil. This for me really helps to combat the sebum, fungus and the inflammation it causes

Dr. Bronner's is a soap concentrate, not a topical.

Distilled water with a small amount of DMSO works well for me, you don't really need all that much to get its penetrative effects. MSM can be used in place of DMSO, but it won't work nearly as well IMO. Dimethyl isosorbide is another penetration enhancer, but it smells strongly of chemicals, and has very trace amounts of formaldehyde in it. I have used both and I vastly prefer DMSO.

Something else I have been toying with in regards to penetration enhancement is urea, as it seems to force moisture into the skin. You could look into that as well, but it's uncharted territory as far as I know.