They're all very simple which makes them attractive. Let me start with the first one, decent signature with a nice border around it. The text should be removed or be white to make it more visible imo. Also, the bottom right is kinda blurry. But overall, it's pretty nice.
- The second one, love the Polaroid thingy you got there. Nice, simple background and text, but again try it out as white and add a little stroke to it. Would look better, I guess.
- The third one, kinda bad compared to the first two. Actually, the only problem here is that there is a lot of empty space and the background is nothing too attractive. You should have worked on a smaller scale imo. And I would give you the same advice with the font colour. Try it out and see how it goes.
- The fourth one, sexy. That describes the graphic. You've used simple but effective techniques and god, it's turned out to be brilliant, honestly. Again, I love the simplicity of the signature. Good choice of yours not to have text in there.
- The fifth one, another pretty good signature, what's that font called?
- The sixth one, the text looks OK. Love the simplicity here as well but don't really like the text in there, floating on top of the signature. Almost looks like a watermark. Rest looks pretty darn awesome. What do you do to get that sweet effect on the main image? Levels adjustment?