The thing about Epic spells is the ritual aspect. With the Epic Spellcasting rules as written, every caster will have given themselves a +5 to every stat, that is permanent. If you assume that the Epic caster has about 30 people who can contribute a 3rd level spell, they can drastically change a charcter. I recommend that you add two house rules:
1. Ritual casting cannot make up more than 50% of the mitigating factors
2. A caster is limited in bonuses by level - Energy seed spells are limited to 1 die/level, fortify stat bonuses are limited to one point per level.
The reason for rule #1 is that it's pretty easy with ritual casters to cast a powerful effect that lasts for days. Since all epic casters have at least two spells they can cast per day, it's possible to have a dozen enchantments going at once, if the duration is long enough. This damps down the power of such an effect.
Rule two is suggested to make higher level people better. With casting, it's all about reducing DCs to cause the effect, so that spells don't cost very much XP. With the number of things available to mitigate costs, it would be nice to have 35th level people cast better spells than 25th, aside from the idea that the 35th level guy will have a Spellcraft skill 10 points higher.
To answer your original question, there's a few things here and there on the Net about Epic spells, with some suggestions. There's a couple of spells in the Book of Exalted Deeds. Honestly, with the abuse possible in it, there aren't that many published spells.