To export a CSV list of your hosting accounts, you need to go to the "Hosting Resources" > "Hosting accounts" section on the left menu.
The "Download a comma-separated-values list" link above the accounts list (a small icon with an arrow pointing down) allows you to export a comma-separated-value list of your hosting accounts. To export a list of your domain names, you need to follow the same link in the "Hosting Resources" > "Domains" section.