I also wouldn't mind a big book of traps, and a big book of usable terrain like in DMG2 (not sure if you can release that stuff.)
I'd also like just plain terrain elements. Give me unique things I can put into a dungeon to add color or give bonuses or penalties... (Like the stuff in the last Dungeoncraft... give me a TON of that stuff I can brows through and pick from...)
I agree with this.
Book of Treacherous Footing
I've been clamoring for this stuff every time this topic comes up. A book of Fantastic Terrain is something I'd buy in a heartbeat. As well as the Dungeoncraft dungeon dressing and plot ponts.
Sites of Interest
A book of adventure sites. Not mini-adventures, not encounters (per se), but stuff to make my brain go "ooh". Wotc's "Worlds and Monsters" Preview book had good examples, where they mentioned an underdark Troglodyte fortress made of hollowed out fungi, and the sentries would hide
inside flaps of the fungus, etc, so they could surround a party. Another examlpe I just thought of, "Here is a hot spring that gushes from the pure heart of the Frozen Mountain. Water from the spring is said to wash out any poison, but the hot spring is the domain of Cragstrider, a surly satyr who can dry up the water with a glare."
I want something that invokes a feeling of wonder or mystery or magic, or anything that would be a great place to have the PCs hear about in legend or in local rumors or have to find in order to do X. That is what I truly
need for my games.
Two product lines which correspond with the above (published under 3e) were "En Route" and "Foul Locales". En Route was just "random encounters" that you could have during travel. Foul Locales were adventure sites (map, background, etc). I would like to see something somewhere in the middle - some adventure sites only need a paragraph to three. Others need a little encounter writeup. (I'd also like to see
roleplaying encounters; En Route had quite a few of those).
Objective Based Encounter design
One other thing. I want to see someone with writing finesse to tackle Objective Based Encounters. The DMG2 mentions it, but doesn't go far enough.
This thread is on the right track, but I want to see someone take these ideas and iron them out into a smoothly running model. "Here's a specific example/encounter. Here are the rules for it." Design the parameters of the mini-game.
[sblock="Example"]
Situation: The Zombic Cult is going to engage in a ritual involving five sites of interest inside the town. If they succeed, a zombie-curse will start to spread (and bad things happen).
Objective: Disable all sites. If an active Ritual Site is not stopped in time, the curse starts. For every site that succeeds, the more powerful the curse.
For the GM: Start with the first Ritual Site. PCs have X rounds to stop the site once it has gone Active.
PCs must do A or B to stop the ritual/deface the glyph/destroy the material (similar to the Countermeasures for a trap, plus any creative idea the PC has).
Here are some obstacles in their way (typical enemies/protections at ritual site).
After Y rounds, one of the 4 sites (roll d4) becomes Active. PCs know when a site becomes Active.
(This Objective can be reskinned to goblins setting fires in a forest to cause a blaze, terrorists setting up bombs, or even NPC enemies attacking five important sites like force field generators/wards, and the PCs must defend them once they start attacking that site. The important thing is getting the rules parameters of the Objective set.)
[/sblock]
Facing the Fair Folk
I would absolutely adore a book dealing with Fey. And I do not mean a book that just says "Here's some stats, have fun". No, I want Fey psychology discussed. How do they act? How do they SEE the world? The PLayers? How about some rules for a fairy revelry (where people can be trapped for all time if they stay at the party and partake of drink/food or dance). Making deals with the fey. Riddles, encounters of non-combat sorts (a pixie prank, challenging a powerful fey to a musical duel).
Misc
The aforementioned Book of Side-Quests or Arcana Unearthed (but BALANCED) wouldn't be a bad investment.