I have used Seesmic on my HTC phone for a long time and it help me manage Twitter and Facebook social networks easily. When I install it on my Nexus 7, the functionality works really well but the the UI is not optimized for tablets.
Best Twitter client app for Nexus 7
* Plume is a beautiful and customizable Twitter client under category of Android social app. I've been using its ad-free version. It was formerly known as Touiteur and now has tablet interface.
Plume support multiple accounts, Tweetmarker, picture preview and share.
* TweetCaster is a must-have Twitter app that's smooth and responsive on the tablet. It features photo/video uploaded, threaded messages, posting to Facebook, multiple size widget with and search tweets.