I've put together a first draft of two of the 20-sided quickie tables. Actually, it's all the tables I did, with the monsters and geography condensed into one table. These are still considered rough: I did some re-arranging of entries and may want to change a few. However, if you already have a formula, you can use these tables just fine.
Table I: People, Actions, and Things
Table II: Monsters, Events, and Places
Update: Table II has been altered so that the creature and habitation types are next to each other, allowing the first three columns to be read as "MONSTER in a MODIFIER/EVENT LOCATION".