The Marsh/Cook Expert set has a nice, neat set of random wilderness encounter tables in the back. Similar tables can be found in other editions. These are pretty nifty in that they cover a wide range of terrain types, providing different encounter sub-tables for each type of terrain, so you won’t see the same monsters in the desert that you ran into in the jungle.
Nonetheless, there’s still a certain lack of variety. Might there not be different monsters on the jungle-covered Isle of Dread than in the rainforest of Hepmonaland? Won’t the humanoid tribes in the hills near Greyhawk be less powerful, numerous and varied than those in the Broken Lands? Surely the partially tamed wilderness in Furyondy isn’t going to be infested with big-ticket monsters that can butcher your 2nd-level party. And what about the demons and undead that should be roaming the downs and barrens of the domain of Iuz? I don’t see them on any of the standard tables.
So yeah, having distinct wilderness encounter tables for each region is awesome. But it’s also a lot of work! Fortunately, there are several quick and dirty way to make an idiosyncratic wilderness encounter chart. See below!
1) Steal it from a module. Are your low-level PCs traversing a marshy shoreline in a civilized — albeit unpleasant — area? Use the encounter tables for Nulb in T1-4: The Temple of Elemental Evil, which are full of relatively weak monsters, including pirates! On the other hand, the dragon-infested encounter table in X10: Red Arrow, Black Shield is well-suited to really nasty badlands where only high-level characters dare to tread.
2) Alter the distribution on the top-level table. Wilderness encounter charts generally have a top-level table which, when rolled upon, sends you to one of many sub-tables. For instance, with a table like this:
… you can just roll a d6 instead. Presto, no more Dragon subtable, and no more dragons!
3) Modify the top-level table to make certain results common. For instance, in the above table, instead of eliminating entries #7 and #8 outright, you could replace them with “7: Merchants” and “8: Brigands” for a dangerous trade route. Alternately, if they’re going through the haunted Bone March, you could bump it up to a d10, with entries of “7: Skeletons”, “8: Zombies”, “9: Ghouls” and “10: Wights” to make the undead far more prevalent.
4) Use the tables as-is, but replace inappropriate or undesired results (maybe you don’t want Frost Giants in this volcanic badlands, or Giant Lizards in that taiga) with something else — either with a specific pre-determined entry, a “Special Replacement Table”, or with a whimsical spur-of-the-moment choice.
Give one of these quick and dirty wilderness encounter mods a try. If you do, let us know how it works for you!