Does anyone know what kind of insurance I need to protect me from some nutcase trying to sue me because they screwed up some advise I gave them over the net.
Personal liability insurance, even for professionals, is very tough to find and grossly expensive when available. In this case, because you're searching for the insurance AFTER an incident occurred, not likely.
On the brighter side, unless you were offering your advice as a licensed, paid, professional, it's unlikely that someone would have cause for doing whatever you suggested. Anything is possible, however. Remember that somewhere a woman is enjoying a substantial amount of money from McDonald's because she didn't believe the fresh coffee she picked up in a drive through was hot!
Finally, read the disclaimer at the bottom of each page of FreeAdvice Forums. Wherever you posted the advice, something similar should have appeared.