This site has dynamic graphics in two different ways.
Dynamic Graphic Libraries
Although I have not created additional graphic libraries this site is designed so that any theme can use an entirely different set of general graphics. Every graphic you see on the home page including all toolbar icons can be easily changed by pointing to a different library. The only reason I have not setup additional graphics libraries is I don't have time to make the graphics(see backgrounds below). It is possible to design a "branded" site with this architecture that has unlimited scalability. Check out the source code of the main frame. Notice in HTML the images have an SRC of "". This is done to support dynamically graphic libraries. All I have to do is add a graphics library and set it when specific theme chosen. For that matter I could let you choose the graphics library AND theme separately. The architecture allows me to adjust as I see fit and more importantly change/maintain it very easily.
This site has dynamic themes. The user can decide color schemes. This creates problems with graphics. Graphics must have a transparent background or at least designed as a box. Using shadows and other effects can cause unexpected results on a different colored background using GIF. Background may be same color as image so an image outline is required. Transparent color in graphics must be chosen wisely. Great care must be taken to ensure all graphics will display properly regardless of users color scheme. Each graphic must be tested for numerous possibilities... even background pictures.