I am a PhD student in Information systems, I would like to have a
research topic dealing with IS, IS Usergap, IS Stereotypes or
something similar. Also, I would like to get some more suggestions,
ideas and topics for a PhD dissertation in the field of Information
Systems

You should probably focus on finding an advisor, since I doubt you'll
be able to do dissertation research on your own, without anyone to
advise you and fund you.  Any prospective advisor should have some
dissertation project ideas you could work on.

Yes, indeed.  Isn't it usual for someone working on a dissertation to
have a senior professor advise him/her, who will be the first to judge
the final work and  approve its submission to others for approval,
someone so familiar with the field that he will know if the
dissertation is original work  - I don't mean that it is not
plagiarism, but that brings new insight to the field?  They're call
"doctor fathers" in Germany, and you have to have one.