What are the symbolic meanings of the characters in "Waiting for Godot"?

There are several ways to read the characters of "Waiting for Godot" as symbolic. I'll provide you with some of the major readings, though for the details, you'll have to do some digging in the text of Beckett's play!

• The physical and the mental. This is best exemplified by Estragon's obsession with his boots, and Vladimir's obsession with his hat - the two represent, respectively, the thinker (V) and the pragmatist (E). Vladimir's breath stinks, and Estragon's feet stink. The two are interlinked and co-dependent, but different in approach. The head, and the feet. The hat and the boots.
  
• Post-apocalyptic tramps. Beckett's play never actually specifies that any of its characters are tramps, but they seem to sleep outside in ditches - and are afraid of some mysterious figures who beat them and can potentially cause them harm. The Eiffel Tower is mentioned, placing the play in a reasonably modern context, and yet it seems that civilisation has disappeared or vanished. Are the two survivors of some horrific global wipeout?
  
• Christianity. The play is packed with references to the Old Testament, and "Godot" is a close aural relation of "God". Are the two men sinners on the road to redemption? Who is Godot? Why does that leaf appear on the tree?
  
• Servant and master. Best exemplified by Pozzo and Lucky and their rope-lead. Vladimir and Estragon also switch roles as servant or master - and the dynamics of dependency and power are constantly at play.