Hold on !  Why 80 characters ?

Well, I think It's common coding standard (May be it's a result of the IBM's 1928 80 column punched card format )

In Sublime text 2, we can add one or more vertical lines after amount of characters (basing on what you setted) like the following: As you can see, I have 3 vertical line on the right side of screen.To set them, just open up your setting file in "Prefernce/ settings-User" menu , and add "rulers": [80,90,100] option :

/* Preferences / settings-User*/
 "color_scheme": "Packages/Color Scheme - Default/Monokai.tmTheme",
 "font_size": 15,
 "rulers": [80,90,100]


The values of array : [80,90,100] are the number of characters  alternately.