Those are cool. Love the idea of the pop out sig. The renders are sharp and clean. Love the textured backgrounds you used. However the text used for your name in the 1st and 3rd sigs aren't so visible. But decent nonetheless. I give them an average 8.5/10
The text is too small and hard to read, although Im a total GFX noob I still think that part could have been better. The popup characters rule though!
You must really like cartoon people with big heads and little bodies. The text effects could be blended better and be made less basic.