To-do:
404 not found.

Contacts:
Nothing, besides my phone contacts (which I don't use besides calls/texts)

Calendars:
If I even do, Google Calendar or the Reminder app on OS X. It's a rare occasion, though.

Note taking:
Either a physical journal or the Notes app on OS X.

Email:
Thunderbird (on OSX), mutt (on Linux, probably will switch to Thunderbird), Webmail (on Windows)

Device syncing:
Mehhh, Notes and Reminders are synced to my phone. I did have Google Chrome on my phone for syncing of bookmarks 'n shit, but I ended up removing it in favor of Safari.