Just bringing up what I see as the biggest issue in watching L4D2 casts atm.
It's rather frustrating not knowing how much health and what class the 4th SI is (especially when it's the tank), and not being able to see the survivors health and items. It would remove a lot of guesswork and make more of the information visual, if we could have a spectator HUD.
I am aware that custom HUD's are banned in tournaments atm because of the way Valve did things, but from the leagues perspective, it would surely be worth allowing casters to use custom HUD's in order to make this a better watching experience. I really think it would be worth talking to league admins, Frustian or whoever does this sort of thing, even Valve themselves, about the possibility of creating a spectator HUD.
From Pwnage's perspective anyway, it would certainly shine a favourable light on you if you could initiate a community service like this

Just my thoughts.