I've been working on WordPress projects for a while and I've realised how difficult it can be to modify existing site, developed by someone else, especially when a lot of different page templates are registred, so you need to spend some time to find out what to edit. I used to echo body_class function, but I needed something more practical.
That's why I've developed Easy page templates info plugin which will add a new column in wp admin->pages and immediately let you know what template file is used for every page, with no need to click on quick edit/edit to grab that info. It also provides an option for filtering pages by available templates.
Hopefully it will speed up someone's theming process.