This page contains links to several papers on the topic of creating "accessible" HTML tables, that is, tables that are in compliance with Section 508.
This paper discusses ways to format complex tables of statistical data in HTML so that they are accessible to visually impaired users and compliant with the provisions of Section 508. The purpose of the paper is to assist HTML developers, and vendors of screen-reader products, to understand what constitutes "coding to the standard" for accessible HTML tables.
Cookbook for Accessible HTML Tables
The solution that (to me personally) seems to be the best. Click HERE for another page illustrating the same basic technique.
Another possible technique for making accessible HTML data tables. Possible, but not especially recommended.