"Yes, but what have you done for us recently?"
We like numbers, as gamers. We like representing the world as modifiers to rolls. But social capital is both horribly represented and really well represented numerically. I'm going to quite happily refer to At-Will's excellent post of "Penniless but not Powerless" and riff from there.
They introduce reputation and fame as part of a currency system which represents the resources that characters have to draw on. In Part 2 they talk about alternate currencies. Here, I'd like to add "Favours."
All social capital, whether implicit or explicit is a way of managing resources. It's a complex (and usually not-conscious) exploration of game-theory's Stag Hunt. People naturally fall into a tit-for-tat pattern with iterated Stag Hunts, because well, cooperation is good, but cooperating with defectors costs resources.
Therefore, favours are an abstract commodity just like fame, reputation, etc. While the posts are about 4e's system, it's trivial to take the idea of "articulated abstract capital" to any given game system. Furthermore, favours are actually quite portable. If I want a favour from you, and you have your own needs beyond what I can do you, I may "know a guy who knows a guy who..." and can exchange services for services. Even with competing factions.
Therefore, we don't have to give players faction-specific currency. The "Favour Wealth" indicates how many markers they hold, how much value they've contributed to various factions. However, people/factions also have short memories, thus the "I know you saved the world... but what have you done for me recently?" For any given faction, referenced on index cards, wave, google docs, have a bullet pointed list of the 5 most recent things the players have done that have impacted the course of the faction.
If the players want something from the faction, they can pay favours. The "discount" of favours, is a function of how positive or negative those last 5 things are.
Thus, players can play in the complex social world and do favours for people and get non-currency rewards. However, the value of their favours fluxes with their fortunes, their ability, and who they're helping or annoying this month. It's also really easy to track and add new factions.
Here are some examples:
The players want a favour from a faction leader that really likes them, they want a squad of thugs to back them up on the next mission.
They've got quite a sum of favours, and their last 5 entries have been positive. These people like them, and they think they will come out ahead if they risk capital on this group. The players pay X favours, whatever would be a currency equivalent, less a discount if appropriate, and they've got a squad of thugs. The DM notes down "Bravo squadron assigned to party." This is a fairly neutral entry, but it pushes the earliest entry off the stack (queue, because it's FIFO, but we won't go into CS here.), factions are fickle. If the squad is slaughtered, in the way of NPCs, that's then added to the stack, and the next earliest is pushed off.
You, as the DM, simply need to refer to these cards or bullets whenever the players want something and can reward favours as treasure when appropriate.
Best Answer
Counters are a really useful tool. You give each player a (for example) red counter per ration they have, or other limited resource they need to spend every set amount of time. The DM gets 23 black counters that are each 1 hour, 5 blue counters that are each 10 mins, 9 green counters that are 1 minute each, and so on. Then when time passes you move a counter onto a 'time passed' pile. This is easy to set up and remember, and the players know that they need to spend a red counter every 8 black counters (if they need to eat 3 times per day).
You can also use this to track time left on spells, by having a separate pool of counters that you also take from whenever you add to the 'time passed' pile. When this pool is empty, then the time on the spell has run out.
If you don't have counters, you can use anything else you have to hand. Things like dice, unused minis, pieces from board games and the like are all good choices. I usually use tiddlywinks because of the small size and the large range of colours. Plus, they're flat so they are easy to store and you can stack them.