Toodledo & Got To Do
[Dec 11, 2010; Personal]
I've been using this bundle for half a year now and am quite happy with it. Both tools provide a similar lightweight Getting Things Done implementation. They get stuff organized a lot quicker than ThinkingRock with its cumbersome by-the-book workflow.
Toodledo is a online to-do list service and acts as cloud store and web access for my tasks. Got To Do is an Android GTD-style app which synchronizes with Toodledo.
There are slight differences between the two tools, like the missing inbox view in Toodledo. However, both tools support task status (which Got To Do uses to assign entries to the inbox) so that no data is lost when synchronizing back and forth.