The frequencies each company is licensed to in an easy to interpret format.
For example: If I want to look at all the mobile phone frequencies for a specific area, I would like to see which companies have certain frequencies.
One way of laying this out in a visual way is something like the NTIA's spectrum allocation chart. The ability to have an excel version of this data (company, frequency, and license call sign a minimum for data) would also be useful.
This information should be more geared towards tasks that work with spectrum, like interference analysis.