A classic task given to a programmer is to make a TOP-N report of some data. Often a TOP within each group of some defined grouping (department, country, product type, etc.) And many times the report should also include the percentage of the total - even though you only display the TOP records.
Many ways can be devised for this and many ways has been used and blogged about and given lectures on. This is nothing new, but it is a technique we often use in many practical cases. One typical case is a top list of best selling items within product groups.