Failing to change the look of the home page from time to time. My changes have been subtle, but they happen from time to time. Difficult to remember domain names. Failing to list your url with your professional directory. Simple graphics are ok.
Consistant graphics are important.
But unprofessional graphics are bad. Lack of content. In consulting I have run across some interesting institutional barriers to mediation services. On the one side is game theory and various approaches that are what many consider fluff. On the other side are solid applications derived from real world models that can be cleanly implemented.