A few thoughts:

I feel that overall the game is a bit lacking in good chaotic quests. There's basically four chaotic quests: Kill Jharod, kill Tywat Pare, kill Thrundarr, kill Guth'Alak. Of these, the middle two are basically never done simply because the rewards (amulet of chaos and amulet of raw steel) don't really justify the effort in attempting them. The other two quests are interesting for some cases, but are still rarely done overall compared to the lawful quests. For players roleplaying chaotic or for Chaos Knights, there is a relative lack of things to do, particularly in the midgame.

What I'd like to see:
-A chaotic quest aimed for characters around level 15. I'd suggest making this quest mutually exclusive with the Griffyard quest, and of similar difficulty. Perhaps the PC could be required to steal something from a village of mist elves, say. There could be two possible routes--a stealth route, where the PC must pickpocket a particular key off of one of the elves in order to access the item, then sneak away steathily, or a fighting route where you just kill everything. I think lore-wise, it would make sense to have the mist elves be predominately caster-types of various sorts (not summoners), but, of course, have few HP. Rewards might be things of interest to a chaotic character and similar power to Griffyard, depending on whether the stealthy or violent method were completed. In the former case, perhaps a ring of invisibility, wand of poison and a pair of seven league boots would be appropriate; in the latter case, perhaps a vampiric eternium weapon (or artifact equivalent), a ring of slaying, and wand of death.

-A quest where wilderness is heavily featured. I've described a possible idea for it here.

-A mid-level (pre-ToEF) quest where the PC must align with one of two mutually exclusive factions. Here's one such option.

-An endgame-level quest suited for characters level 30-40 (perhaps even only available at those levels). Something like the "reclaim the Dwarven Halls" quest above might be nice. A possible reward that might be very nice for a PC at this level would be something that would, let's say, halve the background corruption in the CoC (but not in other areas like the scintillating cave). This might make endgame areas like greater vaults or BDC more amenable to non-ultras without huge stashes of SoCR.