I know that I have learned several things from the first thread, and many others that have hundreds of hours of gameplay are learning about new things.
Some of the highlights from the first thread:
Passageways under / inside the jails.
Odd skeletons on a shoreline.
Picking up or moving bear traps.
Using the Drunken Huntsman shop in Whiterun.
Using target spells or arrows to set off tripwires, string traps, and pressure plates.
Keeping the Jagged Crown for yourself.
Protect yourself from Slaughterfish with a cloak spell.
Use an arrow to disarm the soul gem traps.
Pickpocket the Briarheart from a Forsworn Briarheart to kill him instantly.
Please refer to the original thread for more specifics.
http://www.gamesas.com/topic/1430221-unofficial-i-never-knew-thread-1/
Thanks and enjoy!