Here is what we recommend. If you take a look in the product you will see the following categories:
You might also want to see this brief video about using Qlik DataMarket: Qlik Sense - Using Qlik DataMarket (video)
This is probably the best way, at the moment, to view what is available as these sources will be updated and added to on a regular basis. If there is a particular source your are looking for, please let me know and I can investigate for you.
You can also see a generic listing of topics and packages here: Qlik DataMarket Package Contents
Please mark the appropriate replies as CORRECT / HELPFUL so our team and other members know that your question(s) has been answered to your satisfaction.