Macbeth said:
What other gods might we have heard of?
This is a good question. Though, the answer is not straightforward. I will give you more background on how that works and then work toward an answer that will ultimately still be a bit hazy.
First of all, I don't think you are quite set on knowing the "gods" as used by most campaign sourcebooks. I think you are just as interested in how all the divinities work. There are many beings that can have worshippers and can sometimes grant divine abilities. Most scholars will break them down into Deities and Powers. The key is that Powers seem tied to the land. They live here with the mortal races. Deities live elsewhere. Other planes and such.
Some people maintain that Powers are weaker the Deities. There are many reasons put forward, but the two primary arguements are that Powers share the material plane with a variety of different Powers and that they don't have very many worshippers.
The first arguement sounds good, but falls apart when you start to recognize that some Deities choose to share their home planes. In most cases, there will be one Deity with greater power than the rest. Mortal scholars tend to maintain that this is natural. Weaker Deities must find a patron among the stronger Deities, blah, blah, blah. The truth is that mortals are generally not aware of the politics of the Gods. The ones that claim to have knowledge are not even sure they have the whole story, much less an unbiased story. In any event, the arguement that Powers are weaker the Deities because they share a common plane looses strength when you have other Deities sharing planes.
The second arguement will usually betray the bias of the speaker. Powers are not as interested in having humans worship them. Nor elves, thurgon, durgon, halflings, etc. When you consider the range of creatures in the world, it suddenly changes the perspective on who may or may not have many worshippers. The Powers are akin to gods on earth and are more accessible to some of their worshippers. As well, they tend to have followers amongst groups that the more active mortal races are less likely to concern themselves with.
As an example: Eilanahih is a Power. She chooses one place to reside at a time and she is tied to that place for a definite period of time. She then 'dies' and chooses a new place to exist. She is a Power that champions the Dryads. Some consider her to be the Dryad Goddess. In that role, she also has worshippers amongst Satyrs. There are also Centaurs, Nymphs, Gnomes, Halflings, Treants, a multitude of other fey creatures and the oddball humans that worship her. It is unlikely that you would ever find a temple to her, so she might look relatively weak to traditional priests. Yet, in her place she has worshippers from disparate races and she holds a fair portion of power. Is she weaker than some of the Deities? Certainly she is, but she is also more powerful than many other Deities.
So, my concepts of Gods includes the multitude of Deities and Powers.
That being said, how many are there? Who are they?
Well, in times past, there were literally hundreds of Good Gods. There is a place where these have been documented and it would take you months to catalog them. People have tried, unsuccessfully, through the ages. Oddly enough, they all claim to have completed the cataloging, but when they return the records are damaged or lost, or obviously incomplete.
During the Necromancer Wars, many of the Gods disappeared. Both Good and Evil have lost Gods. Populations were decimated during that time and much was forgotten. Some Gods continued on within one or two remaining communities, some have been wholly forgotten, some became more prominent. Students of religion are taught as much as the instructor knows. Students of history may know some as well. (Students of Religion and History tend to have the best overall chance of identifying something as being the symbol of an ancient god.) Still, every so often, a god will arise that was previously forgotten. Exactly how this all works is unclear to most mortals.
So, what other Gods do you know about? Well, the list is both short and infinite. In a lot of cases, I will just wait until you have exposure to one of the gods and then tell you what you know. With the groups skillsets, this is generally easy. On a purely metagame level, it also allows me to introduce new gods for a specific story. I have the apparatus in place for why the god might exist, and why few people have heard of it, so I don't need to break any aspect of the game to do so. However, that does create some difficulties for the players. It might be harder to speculate on the motives or driving force behind something if it is a religious element you have been previously unaware of. I must counsel a bit of patience and trust in those situations.
Pter the Crusader, the Protector - Pter fights Evil. Evil must be stopped and destroyed. All the good people must be protected from the corruption of evil.
Tholnar the Builder - He is said to have created the world. He encourages his followers to build up what already exists. He expects everyone to learn and to build.
Belmay the Bright - She brought light to the world. Both literally and intellectually. She put the Sun in the skies. The stars are hers as well. As is Knowledge.
Lune - It is unclear exactly what Lune is. Folk-legend says that Crill herself once heard Tholnar refer to Lune as "Eldest" or "Elder". Implying that Lune was around before Tholnar. Lune is worshipped by those that revere the natural world and he has very strongs ties to many of the Powers.
Lorissa the Fey - Literally, Lady Luck. Those involved with risky propositions are often hoping for Lorissa's Smile and dreading Lorissa's Frown. If Lorissa is blessing you at the moment, everything is falling in place for you.
Xanthos - Hey, ask Oceas about Xanthos.
TharahT - (Case sensitive) TharahT is the god of water. Often taking on a masculine appearance, some say this is because of the number of female worshippers TharahT may have. Good, Evil, Law and Chaos all have their place. TharahT maintains equilibrium between all states.
Lord of Deception - The Lord of Deception is, well, deceptive.
Urghol - A long forgotten god (Demon) of Disease. He last had a power base during the Necromancer Wars. There is a disease/poison called Urghol's Breath that feeds on Divine Blessings. If a Cleric succumbs to Urghol's Breath, the cleric is cut off from receiving spells. It is unclear how other divine spellcasters are affected.
That is a partial short list. I may add more later.
