How to change bg-color based on word content

Hi,

I wonder if there is a way to examine every word in a document as it is loaded and
select a bg color for that word.

The idea i have will be used for source code browsing, where each group of functions
will be bg-colored based on the grouping of the function (e.g. util functions, IO, etc..)

I assume that i will provide the look up function that take a word and return a bg-color
(based on config file or a database)

Any advice is appreciated

Oded H