I've recently released an app called Organisa Lite on the Android Market.
It is a task management tool with a easy to use, innovative user interface. It has some really great features like being able to minimise and expand projects and notes. The workspace can be exported to a file which can be used as a back up or shared with colleagues. Also you can update your Android Calendar with any of the dates put into Organisa Lite.
Please do check it out. For more info see my blog http://blog.ssims.co.uk/index.php/2010/10/android-app-organise-yourself-with-organisa-lite/ or the page for the app at http://www.intelligent-architectures.co.uk/mobile/OrganisaLite.html.