No, we don't have a dedicated team/person for web graphics, so help is welcome.
It's perhaps best if you first provide some sample of your work so we can decide if we like it. It could be either something you've done previously, or you could try to do something CS-related right away. (For inspiration: we have a bug tracker that collects CS homepage issues, each item is something that needs doing - http://www.crystalspace3d.org/trac/homepage/report/1
However, please avoid Flash - nothing currently really uses or needs it, and it seems doubtful it's introduction would give any benefits.