Not really by popular demand, but I've had a question or two about it, so here it is - my raid UI:
My unit frames are ShadowedUF and Grid, which makes up for most over my raid overview. I use a variety of grid options for information relay, such as GridMana for the mana bars on the right side. My buttons are Bartender, with a skin called ButtonFacade: Apathy. The cooldown counter you see inside the buttons are OmniCC - the SINGLE most important addon you will have for ret DPS. Above my portrait are some blue bars, these are Classtimer set up to track my procs and a few, selected buffs (you guessed it - seals and the blessings I cover).
I prefer DBM over BigWigs and other bossmods, because it's more cutomizable. Combat text is MSBT, a true bitch to set up, but definitely worth it when you finally get it right. Very neat and tidy, and perfect for tracking health, mana, incoming/outgoing damage and heals. Recount and Omen are obvious choices for me, I've tried Skada but prefer these. Apart from Combuctor for inventory, I don't really have any "hidden" addons, so that's basically it - enjoy!