Article signature figure?

Mica essentially answered your question. To make it slightly more complete: Instead of

\flushright\parbox{5cm}{Daniele Spinosa}

(you don't need the \parbox here) use

\flushright
Daniele Spinosa
\includegraphics[width=2.5cm]{sig.jpg}

(You might want to adjust the 2.5cm.)

First of all, if your signature is scanned as a bitmap file such as PNG or JPG, try to convert it to vector with potrace. If you use Inkscape this is pretty straightforward. Save it as PDF. It will be much prettier.

Then you want to \includegraphics but set the bounding box to make the graphic reserve less space than its actual extent. That produces an effect like you're writing on paper.

Yours TeXnically,

Microspino

\includegraphicics[bb=0 0 144 72]{sig.pdf}

To be honest I've never been good at hacking the bounding box, so if it were me I would use TikZ here:

Microspino

\begin{tikzpicture}
  \usesasboundingbox (0,0) rectangle (5cm,4em); % <--adjust the height if you want
  \node[anchor=south west] {\includegraphics{sig.pdf}};  
\end{tikzpicture}

If you want things on the right you can use \flushright as above.