These are the Secura. We've seen most of them, but the short guy and the blue gimp dude have yet to show up.
The Rapiaus. These guys seem to be the medics and repairmen of the Systemcity. The lady, L://YA has already shown up during the fallout scenes in the pilot.
The Admini appear to be some sort of super-hero class program, with some elemental control abilities. None of them have shown up yet.
These guys, the Errant, appear to be the other villain faction on the show. Glitched programs that have gained super-powers while losing the majority of their sanity. The guy in the middle seems to be the leader, but everything suggests that they're far less of a coherent group than the Virites.
The Virites seem to be the main enemy of the series, serving as the mindless, blindly aggressive horde.
Most of these guys have shown up. Unlike the other groups, it seems like multiples exist of most of the Virite characters - namely the hexagonal guy, the centipede, and the wolf/dog thing. The one on the left has yet to show up, but certainly looks more like an actual character than an archetype.
The Corrus appeared in the background of a couple of scenes, lingering ominously before disappearing. It seems like they're some sort of neutral faction. Some have been suggesting that they're all some sort of ghost program, or corrupted data.