Yes , many editors do that and often become editors to do that . Nothing wrong in doing that as long as you can be objective in describing your website / business.
Of course it is perfectly OK to do this. As the links given by websys clearly explain, the only thing that matters is being honest on your application and impartial in your editing. However, we do not accept editors who wish to add only their own site(s), and such self-interest by an editor can lead to permanent closure of their account.