GitHub profile pages include a neat visualization of commit history that they call the "contributions calendar". This 53x7 grid shows the number of commits and other GitHub interactions that the user performed on each day for the last year.
Each cell in the graph is shaded with one of 5 possible colors. These colors
correspond to the quartiles of the normal distribution over the range
[0, max(v)] where
v is the sum of issues opened, pull requests proposed and commits authored per day.