For the less tech savys will explain more on the matter:
A public API for retrieving all the fine details based around items and heroes, and user profiles with public accesible data.
An API its like a set of functions or standards used by programmers to connect to other services. In this case, I am requesting Riot to make a standard set of functions or access points so that we, the application programmers, can fetch up to date item and champion details, as well as public information of the user profiles (by public information I mean the one aproved by Riot to be freely accessible to third parties).
To give an idea of what could be done if this API was done by Riot, we could make web applications like the ever up to date wow armoury, make item build pages with always up to date item info or phone apps that would be able to query (list but not modify) your mastieries/runes/match history on the go.
So its a very nice win to everyone if this is done, it all depends on the flexibility and robustness of the API provided if it is ever done.
Currently what application developers have to do is follow all the patch notes and do some research on every patch to update their apps/sites. And dont take vacations, etc, otherwise their apps/sites would go outdated quick.