(this is a post written in haste and ignorance and contains thoughts that have not necessarily been taken to any kind of logical conclusion; so who knows if there is anything of value here, or anything that can be taken to a valuable conclusion. Perhaps you will take a chance?)
The other day I was thinking about generating large numbers of Pugs. Pugs are a goblin-y kind of creature that I wrote about when I was DMing the Somewhere North campaign earlier this year. They start as 2/3HD creatures (clerics and chiefs have more 4HD) and are found in various group sizes, from two person scout groups all the way up to 150 strong warbands. And you would not want to look in the old Dwarven Fortresses under the northern hills. Thousands and thousands of them in there.
So. You have two Pugs running from a party. Quickly you roll four d8s and there we go, you can get their HP and know what's what.
But: the Party is ambushed by a Medium group. (dice rolled as I write to illustrate point). They've been lying in wait and are prepared. (6+3d6 leads to 19 Pugs, 6 of them are 3HD, roll for 50% check and one is a 4HD Pug Warlord's Son) So the Medium group is comprised of a 4HD leader, six 3HD Pugs (two of which are Clerics) and twelve 2HD Pugs. That's a lot of dice to roll to stat them up. You can do it, but it seems like a little chore.
Thus: I started thinking, can a reasonable generator be made? Say, roll 2d20 and consult a table that will give Pug numbers, HP values, what they are armed with and so on. Of course, the original conception of the Pug is something that I have put together. There must be a million and one similarly created opponent humanoids.
Here's the interesting thing that was occuring to me as I was sat in Costa: there is something beautifully mathematical about all of this. You create a system to model some kind of objects. It's totally valid to create the objects and move from there too. But in some respects the model is quite complicated in some ways (i.e., if you want to generate a lot of Pugs at once). So can a different model be created (a different means of generating large numbers of opponents) that means fewer dice are rolled, but the result is representative of the larger model?
As I said at the start, none of this is thought through particularly well. I'm just curious.
(and say you had A.N. Other opponent that has 2HD and appears in large groups; if there was a 2d20 table, or something indexed with two d20s or something like it - the result from the d20 rolls in terms of HP would be valid as well potentially, i.e., a group of 2HD zombies might have other features but their HP values could be generated similarly)
(all of this floating around in my head, and partially prompted by Zak S's post about Elegance, which made a connection with the idea of mathematical beauty...)