What do you (or should you) do in your company to reward employees whose salary has reached the maximum of their grade range given that there is no prespective for promotion? 

This is not an unusual situation especially in older companies with long serving employees (e.g. oil companies) or in the case of high performing professionals (individual contributors).  A few of my colleagues and I have discussed this and ended with two possibilities other than the usual bonus or variable pay: Super Max and Bonus at Maximum.  While the latter is just a lump-sum cash payment equaling the base amount of the annual merit, the Sper Max allows for the employees base salary to go beyond the normal maximum if the employee’s performance were to exceed a certain level.  Which of these two methods do you apply/prefer and why? Do you know of/use a different method?