Apps for Android users who also use iOS

So there's a few that work on Android devices to help sync information with your iOS device, such as:

iNotes. Syncs notes between your iOS device, your Mac, and your Android device.

SmoothSync for Calendars. Now since you can sync contacts and mail, calendars can't be natively synced so this app is the solution. Works great.

Any others out there that are need to haves?