A few spectator HUD suggestions
1) An overhead view so you can see the locations of all players and powerups. Especially handy for team-based modes like CTF/TDM/CA where the amount of action going on everywhere can be hard to keep track of, but also useful for duels. An especially good way to present a duel to someone who is unfamiliar with Quake maps, so they can get a mental picture of the overall map geometry easier. Also offers the opportunity for VOD commentators to draw up plays on the overhead map like color commentators for meatspace sports.
2) The ability to show health/armor for *both* duel players in the first person view. Especially useful for VODs where someone else is controlling the camera and I want to see how much health the non-spectated player managed to take away from a fight.
2a) Refine the duel spectator HUD into something more like the score graphic you see in sporting events on TV. Imagine a bar going across the bottom of the screen. Each side of the bar contains the complete set of relevant information for one of the duelers; Their name, a large number for their score, smaller numbers for health and armor, the timer in the middle. Highlight the name of the player who is currently being spectated (no more "who is this VOD showing right now?"). If it doesn't end up too cluttered, show the icons of the weapons each player is currently carrying above their names, perhaps with a shaded bar behind the icon showing how much ammo they are carrying for it.
3) A tracked statistic for map control - The percentage of the total number of hit points spawned into the arena that is picked up by any particular player. If an mh and two yellows spawn, one player picks up the mh and one yellow, and the other picks up the remaining yellow, the first has 75% map control, the other has 25%. I feel that this is at least as important a statistic as weapon accuracy, if not more important.