While I've been guilty of it in the past I dislike nested charts during game play, if I'm going to roll I want to roll and be done with it. This can cause a bit of repetition on a chart with onlty say 1-6 results, a roll of 2 always being 3 orcs in chainmail looking for a goblin slacking off get's a little tedious. A possible Solution, giant exploding tables.
Use 1d100, 1d1000 or even 1d10000 for the body of the table, each entry is a specific encounter with all the details spelled out, exact # of critters, loot and gear carried and even loose motivation. The low side of the chart gets the most common and frequent entries, the high side the least common and odd-ball entries.
Don't just roll the d100/d1000/d10,000 straight out however. Roll a magnitude die first , lower rolls weigh results toward the more common (lower numbers) end of the table and higher numbers give a chance of the odd stuff coming up.
By example let's say you've got a d10,000 under-city encounter table set up with several hundred specific encounters with entries 1 and 2 something like 3 rats scurry in the corner or pair of moleman scouts and 9999 is The Holy See of The Purple King and his body guard of 50 Sword Saints and 10,000 is Buthakap the Lich-King and his 3 vampire brides delivering gifts to the unworthy while riding upon lobotomized beholders. A 1 in 10,000 chance might be a little too likely for the big more extreme events while the rats and moleman scouts will hardly ever bee seen in the are common. This is where the magnitude die comes in: roll a d6 (or some other die) and on a say a 1 or 2 roll but a d10 on the main encounter table on a 3 roll a d30, on a 4 roll 1d100, on a 5 a d1000, on a 6 a D10,000. The lower end of the table becomes fairly likely with the bottom more common ten happening a more then 33% of the time, the top end will only come up 0.0016667% of the time.
One could of course use other dice ranges to play with the concept. A table with 100 entries with a magnitude die can for example still end up limiting the top entries to only come up a 1 in 2000 times if say a d100 is only rolled if the magnitude die a 1d20 and one only rolls a d100 on the chart when a 20 comes up.
Just an idea for now, no giant tables to publish just yet. What do you think oh kind and wise reader?