At my company we haven't found a way to charge more, especially with clients that have internal apps that will only work with IE6. What we have been doing is it

At my company we haven't found a way to charge more, especially with clients that have internal apps that will only work with IE6. What we have been doing is itemizing any hourly work spent on IE6 optimization (hacks). So, at least for clients with multiple projects in the works, it make them think twice about requesting IE6 support on their next project.