Are there any lightning, cold or sonic equivalents to alchemist fire and acid?
[going from admittedly spotty memory here...]
Arcana Unearthed/Evolved has Alchemist's Frost (cold version).
The Eberron Campaign Setting has Alchemist's Frost and Alchemist's Spark (electrical version), as well as Acidic Fire (Acid that then bursts into flame like alchemists fire) and Noxious Smokesticks (weak stinking cloud effect).
Relics & Rituals 2 has Lethene's Kiss (yet another version of Alchemist's Spark), as well as a Slipshod 'grease spell' type substance.
Races of the Dragon has something called the 'ditherbomb,' which is essentially an explosive canister of acid that sprays it all around. I don't remember enough about the mechanics to be useful to anyone who doesn't have the book, 'though.
The Epic Handbook has guidelines for 'advanced' version of Acid and Alchemist's Fire (which no Kobold would be likely to be able to make, but if they've got some leftover from that dragon they used to work for...).
I'm not aware of any alchemical items that do actual sonic damage (as opposed to the thunderstone, which has a sonic effect).
My own batch of kobolds back in college had captured dozens of giant centipedes, and regularly 'milked' them for venom to tip their weapons. They would hurl small javelins by the dozens at threats and then retreat into small sized crawlspaces, to wait for the venom to weaken their foes. They had a large open area in their main chamber, filled with netting and ropes they'd made from vines and monstrous spider webbing, and they clambered along the walls like Aliens, trying to stay out of reach of the party melee classes (sadly, their network of webs and vines was all-too flammable, and didn't last very long. Not their most cunning plan, although it did give them the advantage up until the party started throwing fire around!). Using some sort of weak version of tanglefoot bags (little more than clots of viscous mud, really), they would make ranged attacks at the parties light sources, since they could see fine in the dark, attempting to snuff torches, shatter lanterns and cover continual light items with so much clinging gunk that their light was hidden. Darkness is a *huge* advantage for critters with darkvision fighting parties without, and if only one party member (a dwarf or half-orc, for instance) has darkvision, the kobolds can concentrate fire on the one person who can see them, with tanglefoot bags, caltrops, snare traps, grease-slicks and various other 'spoiler' tactics to keep them from reaching the kobolds.
The vast majority of kobold warrens will be a cakewalk for seasoned adventurers. But kobolds are just as smart as humans, elves, dwarves, etc. and just as likely to pump out the occasional Sun Tzu...