I like Bartender, Healbot, and Auctionator. Bartender's flexibility and power to create a minimalist UI really makes the game an entirely different experience. Auctionator just because I'm lazy to look up things. Healbot because I like mouse binds as opposed to keybinds. Some things are on the keys for my Hpal, but mostly just like the buttons.
I also use CLCret for my Hpal - it allows you to move the holy power bar. Hanging off the nameplate is really a stupid place for a healer that is constantly looking at a raid frame somewhere else on the screen - so I use that to move it.
Someone mentioned Pally power - what exactly does it do now? We basically have one buff (provided there is a druid around) now so the function it used to serve is pretty much gone.