OK I'm looking for a list of the "must see" side quests. I don't mean quests that get you awesome loot (hardly nessecary when street beggars seem to wear daedric armour at higher levels!!!). I mean quests that are particularly imaginative or entertaining. Avoid spoilers please - perhaps just give the name of the quest (if you can remember it), where it starts and a quick non spoilery description of why the quest is worth doing.
To avoid duplication lets assume that the Fighters guild, Mages guild, Thieves Guild, Dark Brotherhood and Arena quest lines have already been covered.
OK Ill kick off:
Quest: "Through a nightmare darkly", starts in Bravil MagesGuild. Its a bit like one of those "Crystal Maze" gameshows.
Quest: "Where Spirits Have lease", starts in an inn in Anvil. A guy down the pub (who seems to be in a hurry to leave town) offers to sell you a house for a knock down price. You just know you are being set up but I'm a sucker for a bargain.
Quest: Can't remember the name but starts in the "Bloated Float" on the waterfront in the Imperial city. This one caught me by surprise. I thought it would be nice to spend a night on this former boat turned into a dockside inn but I certainly didn't expect what happened next.