I broke down and ordered Delving Deeper, despite the fact that money's really tight. I was planning on waiting for the free no-art PDF and deciding afterwards whether to buy the hardcopy, but I've gone with the boxed set anyways. Expect a pseudo-review eventually, comparing Delving Deeper to the Swords & Wizardry Complete rules (which I already have) and to the LBBs.
In the mean time, I direct you to something you may have missed: JD's recent series of random tables for various dungeon features: mists, mirrors, fireplaces, cauldrons, mushrooms and more! I'm not a big fan of d100-style tables, and some of the entries seem a bit extreme, but even if you don't want to roll on a table, there are some good ideas in here, like the doppler mirror or the lycanthrope fog.
My own approach would probably be to wing it with The Random Random Table and the attribute dice map. First, I'd pick a couple keywords that describe components of a feature. For example, a fireplace could have four components (ashes, a flue, a log, a mantle.) Each of these starts with a different letter, which equates to a number on the Random Random Table (1, 4, 5, 7.) Someone else might choose ashes, a flue, a log, heat, and smoke as components instead, for a total of five components.
Roll a number of ten-sided dice equal to the total number of components directly on the attribute map; in this case, roll 4d10. A d10 result that doesn't match one of the numbers associated with a component is ignored. If a die matches one of the numbers, though, there's something special involving that component; where the die lands indicates what's special about it, with each attribute being used as inspiration (Strength could mean a literal test of strength, something that affects strength, or something that is strong.) Dice landing on a border invoke two attributes for inspiration; doubles, triples, or higher matches indicate increasingly more powerful effects.
So, I just rolled, and got a 4 on the border of Dexterity and Charisma and a 1 in Intelligence (the other two dice were junk) That could be interpreted as some kind of "ash elemental" that can create a hypnotic whirlwind around those who disturb the fireplace. For another roll, I get three junk rolls and a 7 on the border of Int and Charisma; perhaps a very beautiful mantle with books of lore on it?