Customizing Viewlets

Is there an easy way to customize viewlets in My Dashboard or on Community pages?

For example, I'd like a viewlet on a community page to list all assets of a certain type.

Or, I'd like to have a viewlet in My Dashboard to show the last 20 assets a user has accessed.

The edit option for Community home pages doesn't let you add anything like this. It just lists some pre-defined choices.

Is what I'm describing possible or is it insanely complicated?