Cured Companions of Lycanthropy - Got Harbinger, just never continued on. This is same character as the Stormcloak above.
Did not even know this could be done. My current player's working his way up through the guild, I'll have to check it out at the end.
1: Return the Thieves Guild to its former glory - Finished the whole main quest line, but never had the patience to keep taking on random jobs hoping they would be in a city that I hadn't completed 5 in yet. I think I only did 2 of those "Special Missions" so far. And afterwards I keep getting more jobs in those cities, yet in some I hadn't visited once yet for them.
2: Discover all the Word Walls - Meh, I'm not big into the whole Dragon Shout concept, mainly I only find the one's that are quest related, but never went out of my way to find any.
3: Collect all of the Stones of Barenziah - Only once have I had them appraised, and now I won't even pick any up.
4: Crimson Nirnroots - After Oblivion, don't even want to try another nirnroot quest. Not even sure what the reward is for it, but its probably not worth it.
5: Reach 100 is any skill other then smithing - I know I'm probably the only person on the forum to say that, but what can I say, my highest character level is 38 (Which was my first character) and I simply raised smithing to 100 to see what the Dragonbone/scale armor looked like.
6: Played any character past level 38 - Simply cannot keep to one character to long. I like role play as much as I can, so once I finish my initial goals for each character, or think of another character idea, I start a new one. Most don't even reach level 25.
7: Cook a meal/make a potion - I'm simply to lazy to collect ingredients to mix together when I can walk into a store and buy a potion/food already made for me. (Usually only raise smithing skill now to improve weapons)
8: Collect all the Dragon Priest Masks - Not really a fan of their look, so I don't go out of my way to find any.
9: Destroy the Dark Brotherhood - Only characters I have who have killed Grendal (Correct name?) are the one's I plan to join the Brotherhood. My other characters would be too good or not the assassin type, therefore would not accept the contract.
10: Collected all the Deadra artifacts - Not even sure if I know them all. I only just got Dawnbreaker a little while ago. (Which is by far now my favorite sword look-wise).
There's probably alot more I have yet to do but can't think of right now or even know about and I've had the game since its midnight release, and haven't played any other game other then MLB 2K12 since then.