I haven't done a list like this for at least a week or two so... some more ideas. (I know some have been discussed already, like transferring room control)
[list=1]
[*]Option to remember password when logging on.
[*]Host should be marked so players know who room host is.
[*]Hosts leaving should automatically pass on room control to the other players in the order that they joined the room.
[*]Host should be able to remove any teams (before game start).
[*]Button to randomize starting positions, option to do this automatically
[*]Option to automatically shuffle team playing order
[*]Teams added should have the same number of hogs as last entered team by default.
[*]Button to start game should be grayed out until all players are ready.
[*]Display game settings (map, scheme etc) in load screen.
[*]Refresh room list automatically on leaving a room.
[*]Customizable weapon delays
[*]More helpful log naming. Perhaps include room host, map name, game scheme, and whether the player was present in the game (or just an observer).
[*]Team health display should update when first joining a game.
[*]Names should be displayed in reverse order when game starts (team with first turn should start at the top).
[*]Should automatically save in-game hog name/health display preferences, or there should be an option in the global game settings like there is with volume
[*]H should home in on whatever the camera would focus on if the mouse hadn't been moved. Plane and napalm shouldn't lock the camera. Camera should stay focused on a hog for long enough after a weapon has been used to allow it to retreat successfully.
[*]Invulnerable hogs on rope shouldn't do 'hurrah' taunt when attacked.
[*]Middle mouse button could reset camera zoom.
[*]It should be possible to precisely aim deagle/shotgun shots after the first without having to release the shift key.
[*]Reclassify rope and parachute as utilities. Define utilities as weapons that don't end turn.
[*]Players dropping out shouldn't trigger "stupid" voice taunt.
[*]Timer should stop the instant the hog with the turn starts drowning.
[*]Skip go shouldn't have a crosshair.
[*]Hogs dropping items from rope shouldn't lose crosshair.
[*]Shouldn't have to press return after esc to clear a message.
[*]Should be possible to move with UFO selected, even when a target hasn't been selected.
[*]Defeated teams could drop off the roster (like in worms).
[/list]