I never cared for DA either. I only have an account there because someone pestered me so much about creating one that I finally told him to just do it for me... he did, and now I use it the way Wivernryder described... as storage. lol.
I do like that you can see how many views you get (which is never many for me, but still). Here you have to be scouted to see that... lame. You can also see how many and who favorited each piece, as well as download totals. Random info, but still nice to have access to.
Someone... BmK, I believe... mentioned to me (just a few weeks ago, in fact) that DA has forums... 'cuz I didn't even know! lol :P I should really check them out someday... maybe... probably won't.
I recently created an account at conceptart.org. I thought it would be inspiring, but it just makes me feel ...inadequate, so I haven't posted anything. It's an intimidating place. Their chow's, cow's etc. turn out some REALLY impressive stuff... not to say the ones here don't, but theirs are just... ridiculous. Like, "I'm gonna go sob in a corner for rest of my life due to my inferiority" kind of ridiculous. I hate that place.