Diaspora is the only FATE game I really like, and I've been thinking of writing a review of it sometime. It rationalises the stunt system to avoid the massive lists of Spirit of the Century and Starblazer Adventures, it has has a good balance between its toolbox qualities and predefined content, something a lot of FATE games struggle with, and it has a lot of interesting innovations in how it presents information to players.
One innovation is the use of relationship maps as conflict maps. Relationship maps are fairly common tools these days for managing NPC casts, and Hack & Slash has a good breakdown of how to use them here. I learnt about them in 2001 from Unknown Armies 2e, and I've used them ever since when I need to keep track of dynamic social situations. By providing a reference for how NPCs feel towards one another and what their goals are, a relationship map allows you to improvise more effectively than if you're trying to juggle it all in your head.
A relationship map of the type that H&S is talking about, or that Unknown Armies teaches you to make (a "web map", I'll call it), isn't really a direct artifact of play though. That is, you don't lay it out on the table and interact with it. It's meant only for referees to consult and update. Stylistically, they tend to present individuals, groups or things as the basic units with attitudes and goals forming connections between them. Diaspora breaks with that and encourages you to map the zones of possible attitudes and goals and then to place the PCs and NPCs on the map as appropriate. It provides clear rules for moving between one zone or the other and for interacting with others (which involves attempting to move them from zone to zone). It provides some examples of multiple layouts, and encourages you to come up with your own. You can see a sample of what one looks like on rpg.net here.
I haven't experimented too much with this system, but I think it's a very strong idea with a lot of potential. I'm in favouring of mapping social situations for the same reason I encourage people to do overland mapping, because it turns what would otherwise be a shapeless succession of vignettes into specific, meaningful choices. I think that the zone concept is particularly valuable because it emphasises individuals' movement between attitudes and towards goals. I don't consider the other type of relationship map useless, but I think they do different things. In fact, they complement one another in most situations where you'd need one or the other.
A zone map and a web map can be extremely useful through their contrast. Web maps are great for hierarchies and other rigid kinds of relationships, especially if the relationships as a whole are not primarily goal oriented. For example, I would build a web map to represent a feudal hierarchy's obligations to one another. A zone map would be a useful complement to that when the PCs decide to rebel against their feudal lord, and need to plan or track where everyone in the hierarchy stands on that issue, and how well they're doing gaining them as allies or enemies. You could even drill down so that a zone map exists for each box on the web map, with the zone progress determining exactly how effective or productive each relationship is, which might be a little unwieldy, though you could probably reuse the map a couple of times for similar relationships.