This would appear to be the best place to start discussion. Please include only a single module and reasoning for choosing the module. Once a significant number of modules have been identified it would be interesting to experiment with the set to determine what features would appear to be missing.
Module - Views
Justification - Currently the simplest method to expose collected data in a tabular form to end users. It easily provides multiple variations on the data and it also allows for manipulation of data in a consistent way.