Ok I think I found another quest bug?
I'm in Riften and I'm doing the "Recover Skooma source infomation" quest and without giving any spoilers, I've killed the person (S.I), I'm in the room where the marker arrow is pointing, I've found the container and I take the information. But that's it! The quest won't continue and the quest arrow doesn't move. I've tried reloading a previous save and I've tried leaving the room and re-entering (initiating the load screens). Still no change.
Anyone else had this?

Make sure you really give the place a good going over. I think I remember that there was more than 1 thing to pick up.

there was only the note in the satchel to get, but also, make sure you open you inventory after you get the note and read it, it is what starts the next part, cause reading the note before you take them does not start the quests, you have to read them after you get them into your inventory

AH! Thanks guys, I'll give that a shot in the morning!

That could very well be the case. The same thing happened with me before the Potema (sp?) city quest in Solitude. Firebeard had a courier deliver me a note. I knew what it was for but didn't bother to read it. I fast travelled to Solitude and kept trying to engage him in conversation but he would only say mundane crap. So then I went to my inventory and read the note. Then upon engaging him again, it worked.

yup, same thing happens with the lighthouse quest, if you read the note before you take it off the body, nothing happens, open inventory and read note and it points you in the direction you need to go

Oh yeah, I forgot about the note. True. Often reading notes/journals is what kicks off the next part of a quest, or starts one.
Also, not sure if you knew, but reading found books, in addition to increasing skills, can give you new map markers or quests.

yup, and listening to guards talk about locations will also put markers out, but only if you stay in range of them for their entire dialogue

Yes, and there's the ghost of a headless horseman that leads you to his grave full of skeletons and treasure. And another one with a head and no horse. Serious.

ya, saw that headless guy, finally managed to follow him to the graveyard and kill everything there, is a hard guy to follow without a horse, as I got waylaid by bandits once and lost him.

I have even been tag teamed by dragons at times.

Yeah, I swear he does it on purpose- drag you through the s**t before letting you get the treasure...
I fgured out that it resets, too- I got better loot the 2nd time I followed him.