Interesting specs:
Prot/holy (non-pvp) (http://www.wowarmory.com/talent-calc.xml?cid=2&tal=503501520000130300000000005032013422310232130330000000000000000000000000000000) - Note: this will be nerfed substantially come 3.2.2
There is a pvp variation of this spec but I'm not familiar with it enough to speak with authority regarding it.
Holy/Prot (utility) (http://www.wowarmory.com/talent-calc.xml?cid=2&tal=503501521000130531005152215032013120300000000000000000000000000000000000000000) - Some of the reading I've done indicates that this is one of the best specs for hardmode/progression healing due to mana efficiency while using the "proper" glyphs. (Glyph of Beacon of Light, Glyph of Holy Light, Glyph of Seal of Wisdom) Gives 50% more up-time to beacon + 100% more up-time on a single cast of SS and more absorption.
"Standard" Holy/ret (http://www.wowarmory.com/talent-calc.xml?cid=2&tal=503501521000130531005152212000000000000000000000000005230050003000000000000000) - This is the spec I use for my healing as of right now. Easy to use and it is fairly well-rounded (Glyph of Holy Light, Glyph of Flash of Light, Glyph of Seal of Light) to handle most small and large-healing jobs.
Tonight I'll be trying the Holy/Prot spec I posted and I'll let you know how good/bad it is. Should be interesting...