I've got about 300 hours in the game--completed the main [haven't trapped or killed Oldving (?)] and Civil War quests and am working on level 51 with several skills at 100. Some quests like Bothiah and the final bit of the DB quest, I have deliberately left incomplete.

But it seems I'm running around doing minor quests...things that sometimes take me back to areas/caves/dungeons i've already been in. I don't know how many times I've killed the giant at one location or another or how many escaped criminals I killed or bandits that I have dispatched, but I feel like there must be some quests that I'm missing.

Anyone have a list of the quests in Skyrim or any obscure questsI might have missed and who to talk with to get them?

http://www.uesp.net/wiki/Skyrim:Quests

Some quests are repeatable, like the ones you mentioned: bounty for bandits or a giant. Every guild has a quest like that too. There's no reason to keep doing them if they bore you.

http://www.uesp.net/wiki/Skyrim:Quests Big quests, obscure quests, even quests Bethesda didn't complete.