Generally a scrum is formed to restart the game after a penalty. Not too dissimilar to hockey when the puck is placed between two men by the ref. Only Rugby the hooker rolls it in-between the two teams locked together in a gentrified brawl!
The best maul; without a doubt it would be the Brittish 2004 world cup team. I'm a true Wallabies fan, but I take my cap off to the lads.