Just heard about this Web site today, vangoghletters.org.
The site design is fantastic. The letter viewer allows one to switch from the original text in Dutch or a translation. There are scholar's notes that can be viewed if one chooses. In another pane, on the opposite side of the screen from the text of the letter, once can choose to view a scan of the letter or referenced works of art.
I plan to spend some time each week reading the letters. There are over 900 of them. I will write here when I find something interesting to write about.