NO martini is a vermouth, like a fermented wine. It's proof is (I'm guessing) 28% proof vs. the 40% proof of vodka, gin or whiskey(if your making Manhattans. As a bartender, only once in my life has someone just drank dry vermouth w/out a second booze mixed with it. Red vermouth is a more common booze to drink on it's own bc of its similarities to Sherry or Dubonett.
For starters, a true martini uses gin, not vodka.Beyond that, it is up to the bartender or whoever as to what kind of vodka you use for a vodka martini. That said, plain vodka appears to be most common.
I would recommend using this recipe to try making a vodka martini, http://www.foodnetwork.com/recipes/the-cookworks/the-classic-vodka-martini-recipe/index.html.
gin
It is a gin or vodka martini made with no vermouth
He drinks a vodka martini "shaken, not stirred."
A vodka martini is often made with 2 parts vodka to 1 part vermouth so 1 1/2 oz vodka and 3/4 oz vermouth.
Vodka Martini (shaken, not stirred) and in recent films, the Vespa Martini
A vodka martini
Martini's
Vodka Martini (shaken, not stirred) and in recent films, the Vespa Martini
Black Star Liner
There are bartender receipe books that you can find on ebay or amazon or even barnes and nobles that would have many drink receipes including vodka martini.