I think the project I've been doing for someone else is pretty much over (maybe one or two other bits to wrap up,) but I'm not quite ready to write up the next infernal neighbor yet. So instead, I'll write a little bit about issues raised in the comments on the post on literacy. How do you determine if a character is literate or not?For me, it's simple: your character is literate unless you choose not to be. This can be either a direct choice ("I'm an illiterate mercenary who doesn't trust stuff with scribblings or engravings on it") or indirect, like choosing to be a barbarian, or an exotic foreigner who might be literate in their homeland, but not the campaign area.
I feel the same way about other general abilities: swimming, riding, building a fire, cooking, making a lean-to. I don't see the point in penalizing players for trivial tasks. If we're talking about something more specialized, that's different. If there's a profession built around a skill or a higher degree of skill, I can see excluding PCs from being able to do it; likewise, if it's a skill from an exotic culture. Sailing and literacy in a foreign script are reasonable exclusions.
I do like the idea of a little randomness for a character's extended background, just to inject a little surprise. Why does that desert nomad know how to sail? It's imagination-fodder!
Whenever a player asks "do I know how to do this?" I'd make a standard d6 Situation roll, adjusted for high/low Int and difficulty of skill; 5+ means yes, your character has that skill. After that, the odds of success are normal ... which means no dice rolling, in most cases, and the skill giving a +1 bonus when a die roll is actually called for.