First of all, I know basically nothing on how to MAKE themes.
All I did was edit the new impression theme (https://wiki.ubuntu.com/Artwork/Incoming/Maverick/ImpressionGtkThemes) to make it have a blueish color scheme.
I thought it went extremely well with the Ubuntu Mono Dark icon theme.
To make my nautilus have the breadcrumbs, I followed this guide:
This theme depends on the current release of the Murrine engine.
Available here: https://launchpad.net/~murrine-daily/+archive/ppa
comments greatly appreciated :)