Don't know if it was documented. Took me awhile to figure out so maybe just me
Purchases from WIFI store: They do not automatically sync back - even if you are on auto. You must right click on your itouch in tunes and there will be a menu to sync purchases.
Poor Mans Notes: Set up a contact in Contacts called notes. Go to edit fields and add notes as a field. You now have notes - which by the way will also sync with your mac/pc - so keep in mind you will now have a weird contact called notes!
Bookmarks/Passwords/Cookies: If you spend some time with bookmarks on your mac - you can come up with a few tabs that are mobile/touch specific. These all sync and then you have a quick way to "tab" around in your touch. If these are in your book marks and you remember cookies - you can also set your logons to the various websites and the touch will now "remember" them when you return
Documented but worth mentioning again!
Battery Life Saver/Extenders:
Turn off WIFI when not using. Turn off wifi auto ask.
Do NOT plug your touch into a mac or PC that sleeps - it will drain the battery and not charge. Turn off sleeping on your mac if using for charging your touch.
Stupid workarounds for "missing" features:
Quikie volume control - use sleep button. Will let you return to the song where you were last at, same for video. (Need to have this set up in settings)