Put everything that needs to be chmodded into one folder
 

I dont know but I would find this easier to manage and maintain.

/new/avatars
/new/groupicons
/new/profilepics
/new/signaturepics
/new/attachments

And while we are at it, I really think the default style should be in its own folder.

ie:

styles/default/
styles/my-custom-style-1/

instead of
images/ads
images/attach
images/avatar
-- etc