XFCE with xubuntu theme
Gnome Shell (with docky and 1 extension)
Gnome Shell (active/menu)
KDE 4.7.2 (without Kubuntu tweaks)
These are all taken from the same system running ubuntu 11.10. Not sure what would be "default" look of them, with the exception of the gnome screenshot with docky (and the date/time extension in the activity bar), these are pretty much what you will find to expect in a default installation of Ubuntu, if you install xfce/kde/Gnome 3.