Sunn doesn't have a drummer and make real songs because that's not what they are about. By "they" I mean Stephen O'Malley, Greg Anderson and a long list of other part-time contributors.
O'Malley and Anderson both are in and have been in several other bands like:
Goatsnake: The most straight forward, sabbathy southern rock with clean vocals, but destructive low guitar tone
Burning Witch: Pretty straight forward doom with screeching Ozzy sound alike on vocals.
Ginnungagap: Less oppresive, more mellow, drone-ish stuff with weird foreign istruments and stuff.
Lotus Eaters: Really mellow stuff with Aaron Turner from Isis among others.
Khanate: You just have to hear it to understand.
Sunn's albums Flight of the Behemoth, Grimmrobe Demos and 00 Void are the most drone. You certainly have to be in a sound listening mindset and not a song hearing mindset. The patterns and buildups/releases are wonderful but you need a long attention span and to clear your mind of everything else.
White1 and White2 are of a different ilk, and they experiment with things much more. (at first Sunn was mostly a tribute to the early Earth albums but with the White albums they evolved into something different).
Black1 is coming out soon and is going to have black metal tinge to it, and they have contributions from a couple of the most heralded american underground black metalers. (When I say Black Metal, I don't mean like Cradle of Filth or Immortal, but the stuff that is patterned after Burzum...one man operations, ambient, lo-fi, experimental).
In an example of how they both celebrate and find the humor in metal, this guy who
is the band Xasthur did some vocals recorded in a coffin that was sitting in the back of a hearse. That, to me, is awesome on more than one level.
Pictures of live aktions:
http://hem.passagen.se/ddmdrej/sunn.htm