Just to add:
Colors schemes are easily made through the KControl module (KControl > Appearance and Theme > Color). Then the color scheme file can be located at ~/.kde/share/apps/kdisplay/color-schemes (filename extension is .kcsrc) so you can share it with others.
@bram85: Do you know of any tutorial to on how to make widget styles and window decorations (both native and for dekorator?). And isn't Qt the one used to make widget styles, or just plain C++? Thanks!
OS: Kubuntu 6.06 LTS (Dapper Drake) | KDE 3.5.3
Computer Specs: AMD Sempron 2200 1.5Ghz | VIA KM266 Pro 8235 chipset | nVidia GeForce MX 4000 128MB DDR-RAM 32-bit AGP 8x