Is there supplementary material that improves the adept NPC class?

Question

The NPC class adept is considered a tier 4 class, so it's theoretically more versatile than tier 5 classes like the fighter, monk, paladin, soulknife, and so on, and the class is a reasonable choice for a PC caster in a low-tier campaign. However, I've not seen any material that makes adepts any better except stuff that improves familiars and the prestige class hexer from Masters of the Wild. (Entering the prestige class requires that a creature be able to cast lightning bolt as a divine spell, and the adept is the only SRD class that can do that.) Even though they're tier 6—like the commoner!—, there's material devoted to the aristocrat NPC class like The Quintessential Aristocrat. But, apparently, no material devoted to the poor adept.

Searching the Web for help with adept is tough: results tend to be about the green star adept, dragonfire adept, and other classes with adept in their names instead.

What additional options are available to the adept? I'm interested in answers like those to this question

P.S. Both D&D 3e and D&D 3.5e material are acceptable. Official material preferred but content from licensed material is acceptable as is third-party material.

Answer 1

The Eberron Campaign Setting introduces the religious adept

The adept's spell list is expanded a little by a variant adept presented in the Eberron Campaign Setting on—appropriately enough—Adepts:

A religious adept is identical to the adept NPC class presented in the Dungeon Master’s Guide (see page 107), with one important exception: The adept can select a single cleric domain. An adept does not gain bonus domain spells as a cleric does, but she adds the spells of her domain to her regular adept spell list and can prepare these domain spells in place of her usual spells.…

If a cleric takes a level in the adept class, he does not get to select a new domain, but he can add the spells from one of his current domains to his adept spell list. Likewise, an adept who takes cleric levels must use her adept domain as one of her two cleric domains. (256)

This allows some significant variation between otherwise generic adepts.

Other texts add a few spells

The following spells are added to the adept spell list by other sources:

• 2nd Level: bewildering substitution [illus] (Complete Champion 116), bewildering visions [illus] (Complete Champion 116), invoke the cerulean sign [evoc] (Lords of Madness 211).
• 4th Level: lesser spell turning [abjur] (Mintiper’s Chapbook Web column “Part 10: Chronicler's Compendium”).
• 5th Level: bewildering mischance [ench] (Complete Champion 116).

There are probably a few other extra spells added to the adept list floating around in other texts, too, but this is what I had at hand.

Answer 2

I am not aware adept handbooks. @HeyICanChan got the additional spells, though I'll note Lords of Madness does not actually list invoke the cerulean sign as an adept spell but specifically says "its magic is nearly universal and can be mastered by all spellcasting classes."

If you're willing to go 3.0 instead of 3.5, Masters of the Wild recommended the following spells be added to the adept list. I've listed the 3.5 sources for when I could fine them.

More Spells for Adepts sidebar, Masters of the Wild, p81 (DotF-Defenders of the Faith, MotW-Masters of the Wild, TaB-Tome and Blood): 0 - dawn (MotW) - SpC, p59 1 - hawkeye (MotW) - SpC, p110 1 - lesser cold orb (TaB) - SpC, p151, (orb of cold, lesser) 1 - scarecrow (MotW) - 2 - choke (TaB) - 2 - decomposition (MotW) - SpC, p61 2 - owl's wisdom (TaB) - PH, p259 3 - beastmask (DotF) - 3 - embrace the wild (MotW) - SpC, p79 3 - enhance familiar (TaB) - SpC, p82 4 - false bravado (MotW) - 4 - languor (MotW) - SpC, p130 4 - weather eye (DotF) - SpC, p238 5 - big sky (MotW) - 5 - ghostform (TaB) - SpC, p103

Here are the other alternate class features I've dug up for adepts from WotC sources: Adept Alternate Class Features:

Familiar – Dragon 280, p60 - Alternative starting familiars. (3.0ED)

Familiar – Dragon 323, p88 - Specialist familiars. (3.5ED)

Familiar – Dragon 341, p96 - Specialist familiars. (3.5ED)

Familiar - Dragon 348, p88 - Unfamiliar territory: focus caster; (arcane reabsorbtion isn't valid as it specifically calls out arcane spells). (3.5ED)

Goblin of Grodd - Into the Dragon's Lair, p86 – An adept of Grodd can rebuke or command shadows as a cleric of the same level. (3.0ED)

Goblin of Grodd - Into the Dragon's Lair, p90-91 – Alternate spell list. (3.0ED)

Kobold - Races of the Dragon, p48 - Alternate spell list: Swap animal trance and daylight with lesser restoration and create food & water, respectively. (3.5ED)

More Spells for Adepts sidebar - Masters of the Wild, p81 - Additional spells from Defenders of the Faith, Masters of the Wild, Tome and Blood. (3.0ED)

Religious Adept – Eberron Campaign Setting, p256 – Add ability to choose a domain from the god worshipped; add domain spells to spell list and gain domain power, treating adept level as cleric level. (3.5ED)

Religious Urban Adept – Sharn: City of Towers, p167 – Alternate spell list, add ability to choose a domain from the god worshipped; add domain spells to spell list and gain domain power, treating adept level as cleric level. (3.5ED)

Urban Adept – Sharn: City of Towers, p167 – Alternate spell list. (3.5ED)