Some of the things we need:
(I'd make all of these things myself if I were any good at it)
--We need more utility-based spells. There are plenty of water-based and ice/snow-based ones from Stormwrack and Frostburn respectively, but we need more fire-based utility spells. Mainly:
--Lavawalking: similar to water-walking, but allows the subject to walk over the surface of magma.
--Non-Stick: What can be more annoying than having magma stick to your body and equipment? Sure, energy protection/resistance spells prevent the damage, but you're still going to have molten lava stick to yourself and your clothes, and when you leave a hot area? Yeah, you're going to have cooled rock adhering to your body. Very annoying. Non-stick would be a spell that prevents magma from adhering to the character and his equipment, but doesn't prevent fire damage. It might prevent other types of viscous substances (say, ooze for instance) from adhering to your body as well, but of course it won't prevent other effects such as acid damage.
--I'll do this one; create salt-based variants of some of the sand spells from Sandstorm. I'll be careful not to violate any copyrights when I post the spells.
Also, some cold/ice-based spells I made:
Shape Ice, Greater
Transmutation [Cold]
This spell is identical to Greater Stone Shape from "Underdark" and the "Spell Compendium", except that it affects ice instead.
Soften Snow and Ice
Transmutation [Cold]
This spell is identical to "Soften Earth and Stone", except that it affects ice. Ice becomes packed snow which is easily molded or shaped, packed snow becomes loose snow, and loose snow becomes powdery snow.
It's more useful than "Thaw" (see Frostburn) on planes of unearthly cold such as Paraelemental Ice and Cania where the temperature is below -50f/-45c (cold enough to where water freezes in mere seconds)
Transmute Ice to Snow
Transmutation [Cold]
This spell is identical to "Transmute Rock to Mud" except that it instead turns ice into loose snow.
It's more useful than "Thaw" (see Frostburn) on planes of unearthly cold such as Paraelemental Ice and Cania where the temperature drops below -50f/-45c (cold enough where water freezes in mere seconds)
Transmute Snow to Ice
Transmutation [Cold]
This spell is identical to "Transmute Mud to Rock", except that it turns loose, packed, or powdery snow into solid ice.
ON SPECIAL MATERIALS
--We need a melt-proof special material for Fire, or at least a form of tempering that makes the metal able to withstand temperatures of 5000 degrees or higher (this would allow it to withstand magma AND avoid becoming weakened due to reaching the half-way-to-melting-point).
--Need a special material for the Ethereal Plane
--Need a crystalline special material for the Quasielemental Plane of Lightning that doesn't attract and is resistant to lightning.
For the quasielemental plane of Lightning allow me to recommend a real-world material called the aerogel, or, more evocatively, frozen smoke. This material is a glass-like foam of silica or carbon -- it's light enough that some versions can float on air, strong enough to hold thousands of times its weight in steady pressure, and highly capacitant, capable of storing a large amount of charge. Its one downside is that it shatters extremely easily to a sharp blow.
This odd cross between air and earth might be found naturally on the Plane of Air near the borders with Ice or Smoke. With its hardness magically enhanced to prevent shattering, it could make good, extremely light armor that did not attract lightning and would probably offer at least some natural electricity resistance. (Without magical enhancement it would not offer any armor protection due to its shattering problems, but it could still be made into a translucent container somewhat resistant to heat and lightning.)