Signs of the Times

"Hobo Symbols of the Great Depression" = Adventurer Symbols of the Megadungeon?

Could be used by the PCs, Thieves Guild, or a secret cult, or found by them while duneoneering, used as hints, misdirection, red herring... 
Several would require a broad interpretation, or even an alternate meaning to incorporate into a fantasy setting.  Could also be adapted as a Random Encounter or Random Dungeon/Town  Design table, or your next Dungeon/Map could be marked with symbols...
Several more charts of varying sizes can be found with an image search.
Original Link 

"Xoology"

I'm not sure what this website is about... Vulcans and Biblical Figures... I dunno.  Anyhow, here's a list of weird creatures from various sources, have fun.

(my favorite)
"dobermantis: (Doberman + mantis) pale green caninoid hexapod with powerful grasping forelimbs"

"Boarcs"

Three On-The-Fly d20 Tables

Nothing you ain't seen before, but handy.  I keep these on an index card for those times when I want to generate something immediately and quickly. 

TRAP                                  JEWELRY                 DUNGEON CREATION

1. ACID                               EARRING                  STRAIGHT 20-50'

2. GAS                                NECKLACE               DOOR, USUAL

3. CALTROPS                    BRACELET                DOOR, UNUSUAL

4 .NEEDLE                         PENDANT                 STAIRS, UP/DOWN 
5 .CHUTE                           ARMBAND                BRANCH, RIGHT 10-60'

6. DOOR (roll again)           BROOCH                   BRANCH, LEFT 10-60'

7. JAW                                STUD                         SPLIT, 45-DEGREE ANGLE

8. PIT                                  RING                          "T" INTERSECTION

9. -LOCKS                          CLASP                       "Y" INTERSECTION

10. -FLOODS                     BUCKLE                     4-WAY, 10-40' ea

11. -SPIKED                       COLLAR                     TURN, LEFT/RIGHT

12. FIRE/OIL                      DIADEM                      WIDENS or NARROWS

13. CRUSHING                  CIRCLET                    SM ROOM, 1 Exit

14. ARROW/DART             CROWN                     SM ROOM, 2 Exits

15. BLOCK, FALLS            GIRDLE                      MED ROOM, 1 Exit

16. SPEAR/SPIKE             TORC                         MED ROOM, 2 Exits

17. GUILLOTINE                ANKLET                     MED ROOM, 2-4 Exits

18. PORTCULLIS              PIERCING                  LRG ROOM, 2-5 Exits

19. COLLAPSING              LOCKET                     CHANGE to NATURAL CAVERN

20. SCYTHE BLADE         OTHER                       ODD SHAPE or FEATURE

"Mul-ti-pass"

Monster Monday 3,

This is possibly the most Lovecraftian thing I ever hope to see...
and I don't even dare to imagine it's
weird appetites and disturbingly Freudian motivations...

...but if anyone is sick enough to stat it up for me,
all I can promise is I'll use it in my game and let you know how it went

The "Thank You for Coming" Potion

Whenever a new Party or Character is created, the PC(s) automatically receive a "Thank You for Coming" (random) Potion, assumed to be part of their starting/current equipment.  Gives 1st Level PCs a little boost, makes new/"replacement" PCs feel welcome, and also makes them a bit less jealous of existing members and their preexisting loot!