A small house rule which I've been using in a slightly modified form in my recent Victorian horror campaign (which reached an unexpectedly explosive conclusion this week).
This rule works especially well for campaigns which are somewhat story-oriented (in that the PCs are involved in a fair amount of town based activity, and interaction with various NPCs and factions plays an important role), and campaigns where little or no use of the standard D&D henchmen rules occurs. Personally I've found that the henchmen rules are virtually
never used in campaigns I run, so I thought it'd be good to come up
with some alternative use of the Charisma stat (in addition to its role
as a modifier to reaction rolls, of course).
Here's what I thought:
Using the standard B/X ability modifiers (3 = -3, 4-5 = -2, 6-8 = -1, 13-15 = +1, 16-17 = +2, 18 = +3), pluses in the Charisma stat mean that the character has a useful contact or ally, while minuses mean the character has an enemy.
Of course, the exact role these allies/enemies play in the campaign, and how much impact they have is up to the DM.
In the Victorian campaign we were just using the allies rule, which worked out really well. It occurred to me yesterday that the rule could be mirrored to give enemies to PCs with low CHA.