How about a feature whereby the user could specify color codes for certain grade ranges? For example, if a student's grade is an A, the cell would be colored green. Cs and Bs would be yellow. Ds could be orange, and Fs could be red? That way, a teacher could tell at a glance which students need what level of support? Could also provide an option for the user to specify the color and point range for each.
Having this on the Total grade would be nice. The user might want the option for this to be applied to individual assignments and grade categories as well, but giving them the option to choose would make it most flexible.