1. A system for customizing an electronic document including a memory and a processor communicatively coupled to the processor, comprising: a tracking module capable of automatically monitoring an interaction of a user with the document on an electronic device for reading the document, wherein the tracking module determines an area of interest of the document based on the user interaction; and a display module capable of altering cumulatively at least one of the appearance or behavior of the document on the electronic device at the area of interest, wherein the cumulative alteration is a function of a variable measure of the user interaction over a range.