Many times, when I am in need of some inspiration, I actually look at the topic list in the DMG (pg 44). I choose one and go from there.
As an example:
#24. "New construction reveals a previously unknown underground tomb"
OK, now... who is/was buried there? Well, #3 mentions a wizard's tomb that has been discovered. So, put them together, and decide that a minor noble decided to build himself a castle in the area and opened the long-forgotten tomb of some ancient wizard.
Great, now that we have the idea, we need to know who is buried there. So, write up the character sheet for the wizard (make him of sufficiently high enough level to deserve such a fine tomb).
Now, what else would you find in a tomb? Undead? Wandering monsters who also found it after it was opened, but before the adventureres got there? Wandering monsters who find it after the adventurers are already underground?
What rooms are in the tomb? Why are they there? Is the tomb actually a part of a larger underground complex? Is it a stand alone?
Well, let's think about this a minute.... The deceased is the great wizard "Ipplepop". He was a 17th level mage, and was the hero of the goblin wars of 10,000 years ago. (although the characters probably won't remember this, as it has escaped memory. He died, and is buried in this magnificent tomb. Of course, you are going to have to have his brial chamber, and- possibly- a room to prepare the body for interrment, and no mage would be without his stores for the afterlife (food, horses, gold and riches, cloth, attendants, etc).
There are also going to need to be some traps to take care of those that are irreverent enough to disturb his peace (blind tunnels with pit traps, falling walls, doors that close behind them, and offer no way out, etc).
Now, in the burial chamber, you can find: a lich, a mummy, a ghost/ghast/spectre/etc, or what-have-you-be as the once great wizard, who- of course attacks thoe adventurers for disturbing his rest... perhaps the wizard became a lich, and was buried "alive", and now he is just going to talk to the adventurers, as he has been so lonely these gone many years... before he kills them.
In the room where the attendants were buried, you might find that some of them are now zombies, and will attack on sight.
In the preparation chamber, you might find various things of no value, but maybe a gem or some such... maybe even the life-force of the lich.
OK, now... what monsters are local population? Orcs? Bubears? Gnolls?
Got the idea???
Hope this helps
