Remember The Milk Syncs perfectly with their website and offers loads of features. This app does require a pro-account but the 25$ are well worth it! Syncs with the online app

Astrid Tasks & To-do List Can sync with several online to-do lists but can also be used as a stand-alone app on your Android device Syncs with the online app

ToodleDroid The Android client for Toodledo and robust and stable to-do list online. Syncs with the online app

Google Tasks Organizer Organize and edit your Google Tasks. Sync with multiple G-Mail and Google Apps accounts. Move tasks easily between accounts. Allows offline editing - syncs automatically with the server when connection is restored. Syncs with the online app

ToDo List Task Manager -Pro A to-do task manager application with a simple but powerful user interface. Offline only

Google Tasks Widget Widget only, provides easy access to Google tasks and allows you to view them on your Android Device Syncs with the online app

To-do List (free trial) A simple application that will allow you to manage your list of "to-do" items. Offline only

GOALS ToDo Full GOALS ToDo is the ultimate personal task manager, featuring a to-do list, Getting Things Done (GTD) support. Integrates with your phone's calendar, maps and contacts Offline only