My style of gaming relies heavily on winging it, DMing by the seat of my pants, often with little more than a few vague ideas and the backstory of the campaign to-date. I'm pretty good at that, but I've had over a quarter-of-a-century of practice, trials, amazing successes and humiliating disasters to guide my way.
If you're not so comfortable playing D&D by ear, and sandbox play works best when you are, frankly, there are lots of tools to lend you a hand. Just recently, these tools seem to have taken a quantum leap forward. First, via The Nine and Thirty Kingdoms, I found Dave Millar's Mapper App. Unlike the random map-builders of yor, this one takes advantage of a number of very cool original geomorphs that have been appearing on various blogs lately. It's got lots of customizability options, and the maps look great.
Mein Deutsch ist nicht so gut, so I'm not sure what all's being discussed at Von der Seifenkiste herab... but I could follow the link to this great collection of Labyrinth Lord tools. The map generator only uses the geomorphs of Risus Monkey. Apart for the occasional bit of repetition, and the things kinda falling off the corners, it's damn near impossible to tell that these maps were not made as one whole, rather than being assembled from bits.
In addition, that site also has various arrangements of the LL monster lists (alphabetically, by region, and by hit dice) and random room and treasure generators, so you can populate your assembled geomorph dungeons.
Speaking of treasures, did you catch Jeff Rients' series on ornamental and semiprecious stones? They include pics (so you can know what it is you're talking about) in addition to brief historical and mythological blurbs on many of them.
Truly, this is a golden age for those of us in gaming in general, not just the old-schoolers. Tools like these are becoming easier to make, and we're finding new resources all the time. I can certainly understand why some folks balk at including a laptop at the table, but I'm getting to the point where not having the resources of the intranetz at my fingertips is annoying, especially when I'm designing a setting or mapping a dungeon. Stuff like this only makes it more so.