Are themes uniquely different from each other in terms of features? Like do they have different features ther than how your GUI looks? if they do please site some example like the FallOutFinal theme from the Haloween theme.
Theme features are based on theme modules. There are a core set of modules that every theme has, but their uses are normally different.
well... you can build all sorts of GUI stuff with xlabel... and heaps of weird script stuff with those modules...
You've got Austerity.
Now get Orb (OTS2!) and Tokidoki.
Yes, there is a lot that can be changed within the scope of the shell.