I find myself swapping out the level 90 talents between fights very often. Here is an amazing Macro from a very clever person to put a button on your bar with whichever talent you have active. No more dragging from your spell book:
Code
#showtooltip
/cast cascade
/cast divine star
/cast halo
/script m_c=GetSpellInfo(121135); m_ds=GetSpellInfo(110744); m_h=GetSpellInfo(120517)
/run SetMacroSpell("90 Talents", GetSpellInfo(m_c) or GetSpellInfo(m_ds) or GetSpellInfo(m_h))
Read the full thread here http://howtopriest.com/viewtopic.php?f=18&t=2391