Affiliations are one of the neat ideas in the Marvel Heroic RPG. They touch upon what I had to say about normal the other day because they are (arguably) the central part of any roll you make in Marvel. That is to say, you could conceivably make a roll where none of your powers, distinctions and such apply, but you simply could not make a roll without using affiliation.
For the unfamiliar, affiliation is basically a measure of the character's interaction with others, measure in three values. One is for actin on your own, one for working with a partner, and one for working with a group. When you take an action, you use the value appropriate to the situation.
Now, this is a great mechanic for a bunch of different reasons.
First, it's a nice shorthand for more sophisticated social mechanics (as one might find in, say, Smallville). It has a social component, and it tells you something important about the character (for example, Wolverine is really good at going solo, while Captain America is a stronger team player) without really bogging things down.
Second, it's concrete enough to have a little bit of a tactical feel to it. Which die you use depends heavily on the fiction, and you can usually choose your actions to play to your strength, but not always. The GM can push things towards a tension point, or certain fiction effects (like, say, a speedball special) might depend on making the less-optimal choice. But, for all that, it's reasonably painless - less-optimal is still not _bad_ (which is an important trick t remember for lightweight tactical engagement).
Third, it really _feels_ appropriate to a comic book. It speaks to solo titles and super-teams and heroic team ups, which are really the meat and drink of super heroic comics.
So here's the catch. like all Cortex+ games, Marvel is crazily hackable, and the first thing people end up bumping their nose against in a Marvel hack is how to bring Affiliation into their game. After all, it's very clearly an awesome mechanic, so converting it is an important step, right?
Well...no. not so much. See, all the reasons that Affiliation works so well in Marvel are reasons you don't want it in your game. It represents something specific to comics which is probably not present in your game. That is to say, most fiction has a certain central dynamic, which is sticks to for the duration. Comics are distinctive in how often that dynamic changes, and how the roles of heroes change. If you can't say the same of your game, then you don't want it.
Instead, you wan to take it out and put it on the shelf, then thoughtfully regard the hole that it left behind. It's an important hole. As I said before, it's the foundational element of building a roll, the thing that comes up EVERY TIME you roll the dice. But at the same time, it's not necessarily the obvious thing - consider that for Marvel, that would probably be powers. From the perspective of supers, that seems far more foundational. The rub is that powers are varied and complex - your foundational die needs to speak to the game more than the action of the game.
Now, there's an easy solution. Just throw in some stats - Mind, Body, Spirit maybe - and you've got a completely functional replacement. But if you do that, you're actively passing up a chance to say something about your game, so don't fall back on that unless you absolutely have to.
Anyway, just something to think about.