This is a copy/pasta of the 'Quests and Dungeons' post from the modding list on my old blog:
I like dungeons. And puzzles. I want some quests I don’t have memorized like a litany. I want a Blight fest that will take me a year to finish. (I also want a unicorn, and for Steve Valentine to read me bedtime stories.)
Quests
Tombs of the Undead by Captain Strange. Three superb dungeon crawls, of varying difficulty. At some points, so brutally difficult (on Nightmare) I want to cry. This is a good thing.
Alley of Murders [mirror] by AmstradHero. A short, lore-appropriate murder-mystery quest in Denerim. Fairly easy, but worth a playthrough.
Standalone quests
A Tale of Orzammar [mirror] by Bioware. An official, unvoiced promotional module. As a prequel for the Dwarf Noble Origin, it offers some insight into dwarven politics. Worth running through at least once.
Thirst by searanox. An extended campaign, set in a non-canon Thedan city. Unvoiced, but entertaining. The different ‘origins’ and mutliple paths make this quite replayable.
A quest to-do list placeholder and notice of intent... thing
I haven’t played these yet, but I’m adding the first five to my install, and I may try one or two of the second group as well.
Castle Cousland [mirror] by dragonagefun. Level 7-9+ (suggested).
Ancient Elven Ruins by Sonmeister. Level 10+ (suggested).
Pints and Quarts Tavern by Sonmeister. Level 15+ (suggested).
Infested Grounds by Sonmeister. Level 15+ (suggested).
Swamp Tower Adventure by Sonmeister. Level 15+ (suggested).
Spiders and Knives by BlackPhi. Adds a little mystery to be solved in Lothering.
Dragon Age Dark Times ACT I by Dark Times Team. Quest is available after completing Broken Tower.
The Bloodworks by Alex Hauser. Quest begins in Denerim.
King Calenhad’s Tomb by dragonagefun. Level 13++ to 17+ (suggested).
Temple Of Vulak by dragonagefun. Level 20++++ (suggested).
Return to Korcari Wilds by Templarioseco. May be incompatible with a lot of other quest mods. Boo.
Quests and Legends by Idomeneas. A huge, sweeping expansion, this quest mod/overhaul adds a companion, new classes and spells, crafting items, some fairly lore-appropriate areas, combat instances, dozens of quests, etc. I’ve never played all the way through the mod, but what I have experienced is enough for me to keep this on my to-do list. (Note: this has since disappeared from the interwebs.)
Quests and Legends - Missing Voice of Valeria by Idomeneas1976. The current version of Q&L is only partially voiced; this workaround restores the the missing voice files (culled from from an earlier version).
A useful thing , maybe
Open All Areas by Noob766. A console script for making closed areas of the map accessible, allowing potentially buggy mod-added quests to be played post-Archdemon without the risk of breaking the OC. Recommended use is on post-game saves only, as it is offered with the caveat that it may bug incomplete games.