Bitten's SpellFlash: Priest replaces Blizzard's default proc highlighting to instead flash a maximum dps rotation for Shadow and some helpful flashes for Discipline and Holy.  You can see all the gory details of the rotation using those links, or the one on the navigation bar to the left.  Download the addon from Curse.com.  If you are having any troubles, check the FAQ and if that doesn't help create a ticket.  If you have a question that the FAQ doesn't answer, leave a comment on the download page.  If you have a suggestion or request to improve the addon, add it or vote for it on the suggestions page.

Bitten's SpellFlash: Atonement is a separate addon to use for easy content when you are a healer but want to contribute as much dps as possible.  You can download it here and see the details here.

Other Languages

My SpellFlash modules don't have much text, but if you'd care to translate the options screen into your language use the this localizations page page for the main Priest module, and this one for the Atonement module.  And be sure to let me know so I can say thanks!