What are the common HTML content widths. What I mean by content is the text of an article.
I know these widths are designed with ad space and stuff and mind, I just don't know what common sizes are. I'm looked on some various random sites and 540 and 480 seem to be fairly common.
Is there a standard size for html content?
Most fixed width sites now adhere to the 960px grid, which combined with a 33% / 66% split (the classic thirds rule) would result in a 633px column with a touch of margin and padding gets you towards the 580px zone.
On top of this, your font size will dictate to you to a certain extent, you don't really want more than 75 characters per line, so smaller font really begs for smaller column width.
Remember, this is about design. That means that people cannot tell you a hard and fast rule as that would take all of the artistry out of the design process.