A rundown on some productivity apps that I use with my iphone

first and foremost, I use google a lot. I have my iphone set to sync all my contacts and calendars with google calendar and contacts

you can also sync the notes from notes.app with your gmail account

evernote is an excellent way to take notes and have them synced across devices

teamviewer is an excellent app that allows you to log in to any windows linux or mac

basecamp is an excellent tool for project management, and you can sync your basecamp calendar to your iphone calendar too