Hootsuite [iPhone, iPad]
|Keeping track of multiple Twitter and social networking accounts on a computer is hard enough, but doing it on a phone or tablet just adds to the difficulties. HootSuite's iOS app is just as useful as the web version and well-designed to boot. Manage all of your personal and business Twitter accounts (plus Facebook, Facebook Pages, LinkedIn, and Foursquare) and arrange them how you like, including up front columns for lists.
Free @ iTunes