There is getting to be quite a bit of new DnL guilds, so I'm just going to put the most popular guilds.

CCC -  It stands for chaos to control to conquer. I guess you would say it is the most  evil you can get.  I think it has about 17 members.  I was in his guild, but I quit when I got my guild approved.  The leader of the guild is Rift. - CCC web page

Mystical Awakening - It is a light guild. that's really all I know. The leader of MA is Akyros. I think that CCC is it's biggest enemy.

Divinitus - Another light guild. This one has some potential.  It is allied with DwD.  The leader of Divinitus is Antaean.

Legion - Don't know what type of guild it is, but I think it is light.  I heard Legion was from another game and it was very powerful.  Anyway, the leader is Azazel.

Explorers - They are just out to look at all the environment of DnL.  I think they accept light or dark.  They won't be much of a threat.