In my current D&D game my players are exploring a sprawling wilderness full of strange creatures and adventures. Populating this place with stuff for my characters to do has been a real challenge but one of the tricks I use is theft. I steal cool ideas from just about everywhere. Here are a few examples:
-I mentioned a book called The Name of the Wind a while ago and it's a great story with a lot of cool ideas. I pulled out the concept of a polite group of bandits as well as a "Tinker" and dropped them right into my game.
The first one was pretty standard. The party was robbed, but rather than the usual gruff bandits these guys were calm,polite and efficient. Giving a distinct personality to this group of bandits and their leader really helped them stand out in the world. Beyond that, having read this character in the book let me role play him much easier and even gave me some cool quotes to drop.
The second idea that I used was the concept of a "Tinker" or traveling merchant. I liked this character in the book but gave it a little twist in my game that my players really liked. This character had a wagon full of cool items but he was not interested in money. He would only trade for other items. So my players were digging through their gear looking for things they could part with and haggling with me to get a better trade.
The Tinker had a few items that would push the story along, a couple that were just cool wondrous items or artifacts, some mundane stuff like rope and candles and also a few items that I thought might be fun from an RP perspective. Things like a bottle of fruit wine and a deck of cards. I was happy to see that my players were interested in these trinkets just as much as the magical artifacts.
-This huge wilderness needs to have a lot of little miniature adventures and self contained stories for the party to discover. I think it's a good idea to have a fun goofy night every so often and so I pulled one of these stories right out of Pokemon. The party met an old Eladrin named Doctor Elim who believes the wilderness is full of strange creatures he calls Jahori and he has tasked himself with their capture and study. When they met the doctor he explained his story like this
"I assure you the Jahori are very real. Technically their full name is Jahori Paelor or little devils in the common tongue. I believe them to be a type of demon or faye creature, somewhere between and imp and a fairy perhaps. They come in many shapes but share a reclusive nature and a propensity for viciousness when discovered. They fight like the spawn of orcus until caught and then they seem to calm down and accept their fate.
These capture spheres are my own design. Once a Jahori has been discovered and sufficiently weakened in battle it can be captured with one of these. The sphere must be thrown out near the wounded creature at which point its own magic will attempt to absorb the beast locking it away in a sort of temporal cage. I am then able to study them in this state and even release them if necessary, although that has not proved wise in the past."
By this point most of the players at the table were either laughing out loud or rolling their eyes. They wanted some information from the doctor but before he would give it he asked them to complete a small quest
"I would like you to take a few of my spheres down to the Samekin River. I believe there is a type of Jahori that makes its home in the rushing waters there. I spotted it once many years ago and have had no luck finding it again. The creature is small perhaps the size of a dog but blue and covered in leathery skin. In walks on four squat bent legs like a lizard but has no tail rather it drags a finned tail like a fish. Its head is wide and flat with a gaping mouth full of round teeth resembling river stones. A tall crest like a sail sits upon the crown of its head and a mass of orange scales sprout from either side of its head at the edges of its mouth. It is a Jahori to be certain but I have named this particular one Ter Thor."
The party walked around in the tall grass around the river for a bit before discovering a group of these monsters. Having to wound and capture the animals made for a fun mechanic. Once the target was bloodied they could toss out a capture sphere. Then they had to roll a d20 and hit a target DC of 25 in order to successfully capture it. Depending on the remaining health of the creature I gave them a corresponding bonus from +6 if it was just barely bloodied up to +23 if it had less than five HP left. Trying to guess just how many hits to deliver after the creature was bloodied was a cool change from just murdering everything they see as fast as they can.
Beyond these examples I also pull ideas from games like World of Warcraft, and anything else I happen to be playing at the time. I also steal from movies, books and board games. I find that as a DM now I really consume all media thinking "how can I use this in my game?"
So my advice to other new DM's out there is, don't feel like you are stuck with the official materials. The books that WOTC puts out are incredible but they aren't the only place to get inspiration.