One of the niftier features of DreamApp is the ability to add your own reports. To do this you usually need to add some new code to your web site that gives access to interesting data.
Once you have installed the new code you simply add a new 'Custom' report type from the domain page, specify what type it is and if it's just for this domain or for all of your domains.
To get you started I've got the attached zip file of 4 examples: A Uptime calculator, a Memory Usage (Good if you have a DreamHost private server), a attached client viewer (who is viewing the web right now, again best for private servers).
To get started download the extras pack here.