Well... I had always planned on coming up with my own skin for Centrafuse but until recently I hadn't bothered trying, but all I can say is wow. Wow, that's a lot of work to do. I understand that perhaps this is how most applications on skinned, but it's terribly a lot of work.
Maybe it's because I have recently done work with WPF (Windows Presentation Framework, Avalon), but I definitely think that is the way to do a UI. I had originally been working on a front end that allowed full extensibility of the UI (both in skinning, and programmatic functionality), and after seeing what skinning is currently available I think I might have to consider going back to it. I love the functionality of Centrafuse but it seems to be fairly limited in extensibility; not only in the skinning, but I've found (written on other threads) that some aspects of the plugin model are lacking.
I understand that a lot of people don't want to use something like WPF for a frontend due to the CPU usage required (although it does have a lot of hardware graphic acceleration), but as for what the UI could provide I think it should be considered.
I'd strongly recommend considering a WPF styled frontend option in the future; allow a basic static skinning system (current system) for people that don't have the hardware, but provide a WPF (or something similar) option for those that want it. With that people could add their own modules ontop of centrafuse, allow a dynamic skin (where you only have to style a single button with colours, etc, and yet they all get automatically styled) that could smoothly integrate with their modules, and allow some really cool graphics (smooth menu transitions, commanding, etc).