I started the optimal clan [o] in early January and then Etoile and Inficio started the vortex clan -V- a few weeks after. We began doing matches and practices on my private clan server. We then invited [GT] members and used a few select players (Dave, Red Dragon, and others) to fill up spots. Just a couple days ago, I got in touch with the elusive Stroggs [S] clan members (who usually play minsta and dm) to have their US-based players join in the fun. Now we have a couple young clans that have sprouted up and I'm doing my best to help them to grow.
The US clan scene has been a bit of a mess before with pseudo clans popping up left and right and then not doing anything active except playing on the public servers. Well, that's changing as of now.

Over the past 3-4 weeks, we've had over 20 pickup matches and now they are happening almost daily as of this week. A big part of that was to get the clan members onto IRC so we could communicate. This is the seed that can grow into something bigger as more players form clans and start to work on advanced team strategy. The clan members have been sharing tips and info with other clan members in the hope that we can all grow as a whole, which I think is useful in helping thinks to move forward.
If there are any North American players that have considered joining a clan, forming a clan, or just having more advanced teamplay, then contact me and we'll get you in the mix with the rest of the group. For absolute beginner players in Nexuiz who are interested in clans, I have been recommending to them to work on some of the basic skills first and then go from there. There are lots of people in the Nexuiz community that can help a player build up their base skills. I'll give you the 411 on that if you need it.
Contact by sending an email or private message through the Nexuiz Ninjaz site (or reply to this thread).
Dokujisan