I can turn sync on/off in the Power Control bar. Which applications actually use this sync setting? Is that only Google-based products (calendar, contacts, gmail) or does it also influence apps like IMAP email, Evernote, etc?
I think you mean the Auto-sync. Go to "Settings -> Accounts & sync". You will find which apps are using the sync function under Manage accounts. Only the apps in the list will be influenced.