This is a discussion on HUD's available within the online poker forums, in the Poker Software & Tools section; Are there free HUD's ,are they any good without subscription and if so which one is best ?
Well if you mean completely free and not time limited trials i know only one - easy poker hud (google it). It works with pokerstars and 888 and in my opinion is very good if you want to start using hud and see how it goes. It shows you just the basic parameters - vpip, pfr and afq but it is more than enough in the beginning. Anyway considering that it is completely free you have nothing to loose.