ToME WikiParaCoon: I have some ideas about changes/additions to the pantheon which I haven't seen discussed anyplace else... so here goes.
We currently have what, 5 gods? Melkor, Eru, Manwe, Yavanna, and Tulkas. My first obvious proposal is to increase the number of available gods. There's more major Valar, after all. I would add at least Ulmo, Aule, Varda, and Mandos.
Changes for Eru: I think Eru is mostly good as he stands. The access to the Divination school seems a little redundant with some of his god spells. But then, I seem to use magic school access more than god spells most often, because piety is sometimes hard to come by, and mana always comes back. I might add a very powerful god spell with a *Destruction* like effect, to echo how the Valar "called upon Eru" to destroy Numenor and bend the world when Ar-Pharazon landed on the shore of Valior.
Changes for Melkor: Melkor is also pretty good as he stands. I'd add access to the fire school for sure, though. That was his element, after all. He needs a powerful god spell as well. Something to pay tribute to his powers of corruption (In the Silmarillion, Melkor could never create anything, only corrupt). Perhaps some high-cost high-level summoning spells, for dragons or demons or undead. Melkor should like orcs/trolls/kobolds/ogres/etc.
Changes for Manwe: I can't think of any changes for Manwe at the moment.
Changes for Yavanna: I can't think of any changes for Yavanna, except to perhaps raise her access level to the nature school from 1/2 to 2/3.
Changes for Tulkas: I don't understand why Tulkas gets 4/5 in the earth school. He's the fighter, the wrestler of the Valar. I'm not sure any of the magic schools really fit him well. I might do away with the school access altogether and increase his other advantages, especially those having to do with fighting. Perhaps at high piety he gives extra blows? Or a high level god spell that confers a number of extra blows per round for a time.
New god, Ulmo: The god of the seas, he should obviously give high access to the water school. Like 4/5, maybe. It should anger him when you kill sea creatures. He should like humans (he was the only Valar to ever talk to or care about humans). Ulmo worshippers should regenerate faster while standing in water, and perhaps always be able to walk through water squares without drowning. One of his god spells could be "flood" or something like it, which allows the player to create a small lake around themselves on open ground (destroy lava?). High level god spells could include more attack options, like whirlpool. Temples would obviously be underwater.
New god, Aule: The smith god, he created the dwarven race. He also is responsible for seeding the world with ores and gems for them to find. Therefore, Aule should like dwarves (and petty-dwarves), and should give high access to the earth school, and medium access to the fire school. Perhaps some low access to divination, enough to get identify at high prayer levels. His god spells should mostly be concerned with enchanting/improving equipment, either permanently or temporarily.
New god, Varda: Queen of the stars. She has to like elves and half-elves, since they're always calling on her and singing about her. Medium access to divination and conveyance and temporal schools. Her god spells should mostly focus on light. That light absorption spell in particular. And a non-damaging illumination spell. And maybe a wizard-light effect. She should grant her followers see invisible at high enough piety.
New god, Mandos: The doom-sayer of the Valar. His real name was Namo, and Mandos was the name of the place he lived, but whatever. He should obviously grant high access to the divination school, and perhaps medium access to the mind school. One of his god spells should be "presage fate". Perhaps a high level god spell could be something along the lines of a very spoily artifact, but that might be too powerful, unless it costs a *lot* of piety to use. I wanted to suggest something about being about to use the undead form power automatically as a Mandos worshipper, you know, to be able to cheat death a little bit. But Mandos might not go along with that 
Anyway, sorry about the rambling format, just getting some ideas out of my head.
Chatter
MassimilianoMarangio: Only a note: Some of the proposed Valar were discussed on the old Forum and were added in the Annals of Ea and Theme modules.
BurbLulls: In fact, all of the suggested Valar are in Theme already, and others like Orome and Nessa are being worked on I believe.
Solorin: According to discussions in the forum, Nienna will be one of the Valar forthcoming in Theme. Nessa is one of the lesser Vala. I don't think she'll be available to worship, but she does sometimes appear in the wilderness. Nessa is of dancing, Nienna of grief and memory.
MayLith: Maybe Nienna shows up if your Companion gets killed? (RIP, Satinka...)
MassimilianoMarangio: In another post it was proposed to expand the gods to a total of 16, Eru, Melkor and all 14 of the Lords and Queens of the Valar.
The remaining Lords of the Valar are:
- Orome
- Lorien
The remaining Queens of the Valar are:
- Nienna
- Este
- Vaire
- Vana
- Nessa
IngeborgNorden: I know only a little about the minor Valar, but here are a few suggestions:
Oromë, as the hunter, should grant beastmaster-like control over non-evil animals (he'd like to see the evil ones, Melkor's corruptions, killed). He'd prefer his priests to wield spears, and perhaps grant some sonic attack spell (as an allusion to his owning Valaroma).
Vairë, Mandos' history-weaving wife, should prefer her priests to wear robes or padded armor. She'd grant decent access to Temporal and Divination spells, because of her knowledge of (and control over) history. She'd probably be friendlier to loremasters--especially bards, since Vairë is also associated with the harp and story-telling.
Estë, a goddess of rest and healing, would probably allow improved recovery for any follower at rest. She dislikes violence (most kills would lower piety), but would grant a powerful Sleep spell as one of her specialties.
(I know so little about the others that I cannot make "playable" suggestions...please accept my apologies!)
DragonAtma: Why limit the game to only valar? At least a few others should be worshippable -- Glaurung and Tom Bombadil, for example, and definitely Sauron for the orcs and such.
- -I suspect because the Valar are the closest things to gods in Tolkien. Tom Bobadil won't do anything outside of his forest; Sauron doesn't grant powers (with the exception of once handing out rings, and those weren't exactly for altruistic reasons!), he only bullies orcs into fighting for him. Generally, a Maia such as Sauron will be greatly below even the weakest of the Valar, and I can't think of any Maiar that granted blessings to worshipers, or even excepted worshipers in the divine sense.