Google Drive is a great tool by Google that allows you to share and create collaborative documents that live online! It is great to grab the app for your phone to easily see your editorial calendar of content for your Instagram posts.
Hootsuite is a social media management tool that allows you to see your social feeds in one place, schedule social media content, and create analytics reports. Free memberships are available.
Feedly is a tool that aggregates your new source websites onto one reader site. They allow you to organize sites by category, easily share content, etc. You can even hook your account up with IFTTT to post articles directly to your social channels!
Unsplash is a free stock photography site where talented photographers submit their content (photos) for anyone to view and use. They are a great go to for grabbing photos quickly for social posts.
Facebook Pages App
Having the Facebook Pages app on your phone is great for managing your Pages on the go. Use it to check notifications, engage with fans, and more!