SE sites use Google Code Prettify for code formatting. While it's still up in the air as to whether we would be able to get SE to use community-voted code formatting, I've been experimenting with Prettify.
There are a few options for line numbering in Prettify, and I was interested to know what everyone thought would be best to use, if we were to have our own formatting.
I will post 3 answers with the different options. Please up- or down-vote according to your preference.
PS: Please don't mind the colors right now, haven't got that far yet.
PPS: I took the code from here in case you are curious.