That's Dr. Ms. Scientist to you!

This fall, my students called me "Professor Scientist", despite the fact that I signed all my emails with my first name. I have to admit, I rather liked it. This was despite the fact, I found out mid-way through the semester, that many of the students didn't realize I had a Ph.D. After they found that out, one particularly incorrigible young man called me "Dr. Professor Scientist".
Which I also rather liked. If/when I teach again, I'll probably lead with the standard "you can call me Dr. Scientist, Prof. Scientist, or Firstname", and let the culture of the institution guide the students' responses. But this leads to the question: how do you wish to be addressed? I'm a young woman and I don't look my age. In particular, I want people to realize that I have done the work and jumped through the hoops to get that Ph.D., but I don't want to come off as pompous. For now, I put the "Ph.D." part in my email signature and write out my full name without the title at the end of the important emails. Getting introduced is a whole 'nother thing, especially as a post-doc, and especially to people who don't know what a post-doc is. Does one say, "I'm Dr. Scientist"?

So how do you sign your name? Do you put your qualifications front and center?

I'm not the only one thinking about this - this post has another perspective, as well as this post of forms of address when being interviewed. And speaking of interviewing...colleagues pointed me to this crowd-sourced wiki on current open positions, and if there's any word on the hiring process. I know I'll be checking it compulsively.