I just published another post on Data on the Rocks, a superblog with writers from around the world sharing their knowledge about the Qlik ecosystem.
Adding helpful hover text to sparklines (Data on the Rocks)
This post demonstrates how to add custom hover text to your tables, pre-empting questions and improving clarity for people who use your solutions.
Generally, you can override default hover text using the Dual function, inserting your own text as the first parameter. Crafting a display with formatted, labeled values from all data points requires a bit more work (and the Aggr function), and the post incrementally steps you through the process to a fully built solution.
I also included also a bonus hack using the same technique to embed help text, from the mind of Karl Pover.