In d20 Modern, your character starts with an occupation, which is sort of a suite of augmentations to your class skills, a little bump to your starting Wealth modifier and maybe access to a bonus feat. It is meant to incorporate not just your character's work history but more of a general sense of his or her past before the campaign begins at 1st level overall. It's kind of the first decision you make about your character after deciding on which kind of Hero you are (Strong, fast, etc, since all the playable classes are based on the six primary ability scores) and presents you with a choice between enhancing the skills and reinforcing a playstyle that your character would already be well-suited for, or shoring up perceived weaknesses to allow you to pick up a skill or two you might not normally be able to put ranks in.
I adapted something like this for an all-dwarf Pathfinder game I ran a few years ago inspired by Norse mythology. One of the things that makes the Occupation system in Modern essential is the fact that the default assumption about the setting is that it takes place in the real world and everyone will be playing a human. Of the playable races from D&D, the human is easily one that provides a foundation you can build pretty much anything on. But it still helps to spice things up a bit to further differentiate one character from the next, especially if they're both playing the same class. This was doubly important in an all-dwarf game because dwarves have such a strong sense of cultural identity. A dwarf is a dwarf is a dwarf, in very broad strokes; so in addition to tweaking some of the stuff that might discourage someone from playing, say, a paladin or sorcerer, I thought I would implement my version of the Occupation system.
In addition to letting each character take a single level in a NPC class (Adept, Aristocrat, Commoner or Expert), which narrowed the field in terms of which starting traits they could pick from, everyone had to decide at the beginning of character creation what kind of life their character had while growing up. Dwarven society in that campaign was rigidly caste-based, with your clan's social standing making a lot of decisions for you. So if you wanted to play someone from one of the high-and-mighty families that make up the upper crust, you could do that, and it would net you a bonus feat as well as some other modifiers. But people from lower socioeconomic brackets might respond to you differently than they would one of their peers. At the other end of the spectrum, you could play a clanless exile, but there were obvious consequences for that beyond what is hard-wired into the rules.
These two additions to the character creation process helped to flesh out some of the most important aspects about the PCs' identities - where they came from and what kind of life they led before deciding to become an adventurer. It's not strictly necessary for most games and I don't necessarily think that every bit of minutiae about your character's personality or identity needs to be quantified with game mechanics. But in this case nobody playing ever thought for a second that one character in the party was just like someone else, which is pretty cool since they were all four feet tall with big bushy beards and carrying axes and warhammers.