At this moment I know of Unity which looks much better than the default Gnome desktop that comes in 11.04. Also Compiz adds effects so that enhances the view. But what about other tools that make the view of the desktop much more pleasant to see.
To tweak Compiz you can install
CompizConfig Settings Manager.
It has many options, some of them
might break your user interface so
Conky is a system monitor that
can display just about anything,
either on your root desktop or in
its own window. Conky has many
built-in objects, as well as the
ability to execute external programs
or scripts (either external or
through built-in lua support). It is
not easy to configure Conky, but you
can download many pre-configured
files. Tech Drive-in featured
some really great Conky themes not
so long ago. OMG! Ubuntu! also
featured some Conky themes.