It would be nice to be able to select multiple students as absent/tardy at once. For example, recently the entire freshman class went on a field trip, and I had to individually click the drop-down list and choose Absent/Excused for each student. Another example: large groups of students arriving tardy for the same (excused/unexcused) reason. It would save time on the teacher's end.

As for suggestions on how to implement, perhaps something similar to the Bulk assign points option in the Gradebook (as that's where I drew inspiration for this suggestion).