One feature of Google Docs is a template for a gradebook which is extremely useful and time-saving.
One of the options in Google Docs is Sheets (spreadsheets) and a template called Gradebook is ready-made for saving. Never keep your grades by pencil and paper again!
There are three tabs on the bottom for "Overview", "Grades", and "Individual Report". On the Overview page, you get a very nice breakdown of the class as a whole with letter grades and two bar charts for grade distribution and performance per quiz.
Here's the tab where you put your grades in. The grades automatically generate a class average by quiz and average by student with a letter grade appended. That part at the end - Average, Final Exam, and weighting, I put in myself using simple formulae.
The Individual reports are extremely useful for both parents and students in seeing how they are doing per quiz as well as how they are ranking compared to the class average.