Check out GQueues
While it is cloud-based, the offline functionality on my Android phone works great. Then, I just use online when in the office. I'm a consultant too. It is very easy & intuitive to use and set-up. I've customized it for my GTD application and share to-do's with my assistant and Finance Manager through it as well. Love it.
Been using GQueues for about a month now. It syncs beautifully with GCal and has a ton of useful features. I particularly like the Google extension and the drag and drop facility which makes it very fast and low overhead.
Originally Posted by developPEOPLE
Shame about the garish colours though. The UI looks like a an experiment from the 70's gone wrong. Personally I don't like the Android offline feature much. There is no home button so you have to fire up the browser to get it running. Too many steps if you need quick access - which on a mobile you usually do.