Step 1: Make a spreadsheet
The cells have to be really small. The rows are 0.1 inch high to match the 0.1 inch spacing of the ATMega 168 pins. By trial and error, I found that the smallest font I could use was 6 point Arial Narrow, and the column widths are 0.12 inches for the pin numbers (columns A, D; F, I; and K, N), and the pin labels can be 0.18 inches wide (columns B,C; G,H; and L,M). Once I made one chart, I just duplicated the chart several times so I didn't have to use one sheet of paper to print out one tiny label.
The asterisks by some of the pin labels, D3, D6, etc., indicate that these pins support pulse width modulation, PWM.
UPDATE: Users have reported trouble saving the Open Office .ods file. It gets saved as a file with a .tmp file extention. Instead, right click on the file and select Save File As, and enter the name you desire with a .ods file extension.
To save you the time of creating the chart, the Open Office spreadsheet, ATMega168.ods is attached.