Been looking around on the web for one of these, but I'm only finding node.js/ruby hosted implementations.
I'm keen to have a DynamoDB app, something like that of the navicat ilk that comes with an msi installer to get running quickly.
Maybe there's a valid reason as to why one of these doesn't exist yet?
I'm not aware of a dedicated desktop application for using Amazon DynamoDB from Windows yet.
However, the AWS Toolkits for Eclipse and Visual Studio both allow you to create tables, insert and edit data, initiate table scans, and more, straight from your local development environment (see the introductory post AWS Toolkits for Eclipse and Visual Studio Now Support DynamoDB).
So depending on your use case this might be all you need (or even better, if this is targeting a development scenario).
The AWS team has just announced the option to Explore Your DynamoDB Tables Using the AWS Management Console as well:
You can now view and modify the contents of your DynamoDB tables from within the AWS Management Console. With the addition of this new feature, you can learn by doing -- trying out a number of DynamoDB features without even writing any code. You can create a table, add some items, and see them in the table, all through a very clean and simple user interface.
This is obviously a very convenient addition to the rich client options referenced in my initial answer above, please check out the post itself for a short illustrated tour to help you get started.