Need some good rituals though. The ones that are in are cool, dont get me wrong, but there should be more than one that does benefit the caster.. there doesnt seem much point to spend all that time building a ritual that is going to level your army as much as everyones elses. Of course they dont have to be of that magnitude..
A couple random ideas off the top of my head-
Utterdark (ripped from Dominions 2

) - Req 3 entropy, 1 death. All other civilizations can only see directly around their units for 5? turns (i.e. explored territory re-covered in fog of war.) During the duration, small chance of barbarian Nightmares spawning near enemy civ cities. Medium build time, building removed after 25 turns to limit spam.
Favorable Winds - Your flying units have double movement for 3 turns. Req 2 Air, quick build time, building removed after 10 turns to limit spam. (needs flying units, and Air mana, but you know..)
Frendly Currents - Your naval units have double movement for 3 turns. Req 2 water, quick build time, building removed after 10 turns to limit spam.
Planar Lock - No one can summon for 6 turns (all summoners get the Casted promotion automatically.) Does not affect Guardian Vines, Call Tiger, or Raise Dead. Req 2 Dimensional, quick build time, building removed after 21 turns to limit spam.
Mana Disruption - 40% chance of any enemy mana nodes getting razed on the next turn. Req 2 Metamagic (if there is metamagic mana), medium build time, building removed after 30-40 turns.
Just random ideas, like I said, for national wonder rituals. Planar lock probably wouldnt fit that, really, but whatever. Obviously not gonna happen soon, but hey, someday, more rituals/expanded ritual system is something I would definately love to see! Here's lookin at you, Fire phase
Edit: Another random idea, jsut to throw it out there. To counter the Ritual that causes to sun to heat up, forget the name -
Ice Age - Req 5 Water, long build time, building never disappears unless destroyed - Oceans slowly turn to ice, and land, beginning near coasts, to tundra.
Edit 2: Another random idea - Some kind of "spy" unit that can sneak into an enemy (or maybe even friendly, with hidden nationality) city and destroy a ritual building, or disrupt one in progress.