Examples of cool apps you might want to build:

1. A Salesforce lead tracker, where you can take notes and add/view data on customers.
2. A feature tracking dashboard, that allows you to create or change features we track in the database.
3. A core business metric visualization dashboard, that lets you graphically view your business trends.
4. A Github Dashboard, where you can see all PR information, i.e. unassigned, to review, pending review and to merge.
5. An online e-commerce dashboard, where you can visually track the products you currently have on sale and add or remove products from this dashboard.
6. An AWS S3 File Explorer: a dashboard that enables you to upload, download, and inspect the S3 Buckets in your AWS account.
7. An app with graphs to represent some data source of interest. It is ideal to have a set of filters to change the view of the graphs and the data shown. The larger the variety of types of graphs used the better, i.e. bar charts, pie charts, line graphs etc.