I'm using the dark green one briefly here to get a taste for it.... and I find the text a little hard to read. Could the colour of all dark green text be changed to #6F8255? Onmouseover could be #B7C0AA. Both of these colours are already somewhere in the colour scheme, I just picked them out.
Just a thought, I think it needs to be a little more readable.
What version of vB do we have here? Maybe you could note that somewhere in the sitewide footer along with "Powered by vBulletin" ect. ect.
Anyways, a few skins I like:
vB 3.7
Webber Classic - vBulletin.org Forum
Rooq Classic - vBulletin.org Forum - this is okay for a generic "plain" skin
vb 3.6
Chestnut Style - vBulletin.org Forum - "Chesnut" I REALLY LIKE THIS ONE!!
BlaK-Ice - vBulletin.org Forum - I prefer this MUCH over the our current dark themes
vB 3.5 (I think, ... I found these on another forum... quite simple skins, are they usable?)
vB Skins - Powered by vBulletin - some light green
Grr... well, I'll keep looking for more, I'm getting called for dinner... *leaves*