Monster Geographica series 200 page 3.5 OGC monster compilations along terrain themes organized by CR. No art but you could pick up the companion
Counter Collections by Fiery Dragon.
Bits of series by Tabletop Adventures. 100 Boxed text descriptions for various terrain types plus little 3.5 bits like new hazards. Very useful for adding ready to use at the table descriptions, with enough entries for use as a random generator if you want.
Book of Templates by Silverthorne Games. I like it better than the advanced bestiary by Green Ronin. I particularly like the original 3.0 BoT's elemental templates, best of the half dozen or so versions I've seen in various sources including
WotC. Their minor magicks book of non adventuring cantrips and their race books are nice too.
E.N. Publishing has a lot of neat stuff.
1 War of the Burning Sky, 1-20 Adventure path with war theme and lots of non dungeon adventures.
2 EN Critter series, 3.5 medium-sized critter books based on terrains with a neat little background setting.
3 The Fantastic Science, a wierd science as new type of magic (arcane/divine/psionic/tech) sourcebook with a neat warlock style alt caster class in the back of it.
The Argyle Lorebook A neat points of light 3.5 setting, set 100 years after a magical empire is struck down by magical plague leaving wild monsters, summoned demons, lost wizard ruins in its wake with small villages fighting to eke out survival after the collapse of high magical civilization.
Bastion Press has some good stuff. I like Complete Minions, a 3.5 monster book, and Oathbound/Wildwood. Oathbound is huge high magic setting where creatures from all over are sucked in like in old ravenloft, empowered and encouraged to struggle against each other to attain ever greater power under the observation of powerful divine overseers. Good reasons to have a ton of D&D fantasy races, classes, cultures, monsters, etc. in the party and in the setting interacting with each other.
For 3.5 Psionics you want
Dreamscarred Press with their Untapped Potential and series of short class and psionic race books. Good quality stuff in a field without much support (
WotC, Hyperconscious by Malhavoc, and these guys are the big three).
DragonWing Games is a successor to Bastion and has their later stuff including the "Into the" series of terrain books, Torn Asunder (a d20 crit book with easy to implement crit system that layers on top of normal 3.5 crit system confirmation roll) and lore of the gods (real world ancient mythology god book).
Lazy GM series of 3.5 statblocks for generic humanoids of specific types. Super useful if using one race as big campaign enemy and want varieties of standard, appropriate enemies (warriors, skirmishers, shamen, mounted, at various levels/CR).
Betabunny, I like both their predators book of 3.5 stats for real world predator animals, and their apes of nature and myth with the emphasis of intelligent pulpy apes.
Living Imagination has a fantastic ritual rules set for 3.5 in Spellbound. Their Broadsides has the most realistic ship movement rules I've seen incorporating momentum and wind directions into tactical ship to ship combat, but its a bit crunchier than most want for their pirate games. Streets of Silver is a huge 3.5 renaissance style city.
Bad Axe Games has a nice little ley line magic system in its elf book. I wish he would put the whole Grim Tales Book online for sale.
RPGObjects has a nice
Legends of Fantasy line with mythic Japan and Camelot and dark ages series with tons of new classes and using a nonvancian d20 magic system based on skill rolls.
I'm also a little partial to
The Le's unorthodox class books and the viking one. I got great flavor out of unorthodox pirates for my freeport game.