Hootsuite – Write when convenient, schedule to post over time; share content among multiple social media profiles (Twitter, Facebook, Google+, LinkedIn, Instagram, Pinterest & more), get analytics reports. Free version allows you to work with up to three profiles.
Tweetdeck - Twitter management and analytics tool. Free.
Everypost: iOS app that lets you manage multiple social networks at once from your phone or tablet.
The popular free link-shrinkers bit.ly and ow.ly (when used with Hootswuite) not only let you convert long URLs to short one, they now provide analytics about how those links get used.
See also: The post below for content from Sea Grant Week 2014 social media workshop