The Serenity RPG provides several large organizations for Gamemasters to use but they aren't described in as much detail as I would prefer. The following organization is a prototype for the style and depth of description I think a Gamemaster would appreciate. Comments welcome.
"The Long Reach? That's them doctors, right? Good folk, I guess. Kinda like priests who know how to save more than your soul and that's mighty valuable out here. Never had to go 'em myself, but they saved my cousin's leg back in the miner riots of '06. Not many folk are willin' to cause trouble for good folk like that." - Festus Wright, Street Interview, Eavesdown Docks.
Long Reach Inc is a registered charitable organization within the Alliance and receives the appropriate tax considerations. They have no other formal standing within the Alliance.
The Long Reach is a loose association of doctors and other people willing to sacrifice everything to bring medicine and hope to the most destitute and hopeless holes in the 'Verse. They are primarily a group of doctors who travel the Rim visiting small colonies, settlements, mining towns, and the like, tending to the people as best they can. They struggle to fill one of the Alliance's most notorious gaps in serving its people.
The Alliance has no official relationship with the Long Reach and usually they have to make their own way in the 'Verse. (There are rumors of sympathetic Alliance officers leaking supplies to LR groups or giving them unregistered travel to hot spots.) Usually the LR have to hire vessels to ship their gear, medicines, and doctors. They have a few ships that they own, with the crew of each ship counting as Long Reach members.
While initially conceived as a non-player organization, the Long Reach would serve well as a more altruistic campaign theme with characters being all members. They could still have Browncoat or Alliance sympathies, but you would avoid the pattern of "ship for hire" set by the TV show and movie. The PCs could begin as a Long Reach team, catching rides with whatever ships they could, eventually graduating to their own ship either through salvage, a wealthy benefactor, or the like. Their "missions" could be directed or suggested by Long Reach headquarters, or they could be self-directed.
The Long Reach can stick its nose in places where people might otherwise not get involved. Whether the PCs are members or just a hired ship, the LR can get entangled in all sorts of adventures: discovering corporate oppression of workers, uncovering Alliance secret operations or 'experiments', even facing down evil men on the smallest scale.
One of the nice aspects of a Long Reach-oriented campaign is that the PCs aren't alone in the 'Verse. They can meet fellow Reachers for comaraderie, cooperation, and aid. A Long Reach member can be identified by the leather jackets (bomber-style) with the Long Reach logo on the shoulder. Members can usually find the local clinic and crash for the night, get some fresh supplies, hear the latest rumors, connect with old friends, get a hot meal, etc.
The Long Reach is technically headquartered on Ariel where it was founded. The offices there are primarily a fund-raising and recruiting face to the organization, snagging young, idealistic medical professionals as they graduate from Ariel's prestigious universities. They are a fairly successful charitable organization, letting Core worlders assuage their guilt over the plight of the Rim worlders with a small donation. The Ariel offices also house a residential facility for ailing or aged members of the organization (their retirement plan).
On the Border and Rim planets, there is usually a Long Reach clinic or office in the major and even minor cities. Towns and smaller settlements get visited as often as personnel, supplies, and money permit.
Total Membership of the Long Reach is quite fluid, but averages about 100 men and women. There are about twenty staff in the Ariel offices. There are core teams of 3-4 people in the major cities of the Border and Rim planet. The rest are mobile teams, working their way in long circuits across the settled planets.
I hope this has been of interest and informative for Serenity GMs. I'd also suggest reading through our Creative GM's Workshop. Jim Davenport