so far the only theme that is anything more than just different colors of the same old thing is the LCARS, Id love to see more themes like this, as a matter of fact I dont think LCARS should be referred to as a theme, but rather a SKIN, the difference seems minor(unless you have seen LCARS)
My handheld experience started with the palm IIIxe(the cool guys 3 series, it had 4megs, I think its been a long while) But when palm OS went color, skinning became a big part of the customization of your device.
Id like to see more themes/skins for the NIT.

BhanG