How can I create a 'Nutrition Facts' label?

Here's my take.

_{I had to wait for a delayed train. ;-)}

\documentclass[border=2]{standalone}
\usepackage{xparse}
\usepackage{booktabs}
\newlength{\NFwidth}
\setlength{\NFwidth}{2.5in}

\NewDocumentCommand{\NFelement}{mmm}{\large\textbf{#1} #2\hfill #3}
\NewDocumentCommand{\NFline}{O{l}m}{\makebox[\NFwidth][#1]{#2}}
\NewDocumentCommand{\NFentry}{sm}{%
  \makebox[.5\NFwidth][l]{\large
    \IfBooleanT{#1}{\makebox[0pt][r]{\textbullet\ }}%
    #2}\ignorespaces}
\NewDocumentCommand{\NFtext}{+m}
 {\parbox{\NFwidth}{\raggedright#1}}

\newcommand{\NFtitle}{\multicolumn{1}{c}{\Huge\bfseries Nutrition Facts}}

\newcommand{\NFRULE}{\midrule[6pt]}
\newcommand{\NFRule}{\midrule[3pt]}
\newcommand{\NFrule}{\midrule}

\begin{document}
\sffamily
\fbox{%
\begin{tabular}{@{}p{\NFwidth}@{}}
\NFtitle\\
\NFtext{Serving Size 2 tbsp.\ (33\,g)}\\
\NFtext{Servings Per Container 7}\\
\NFRULE
\NFline{Amount Per Serving}\\
\NFrule
\NFelement{Calories}{20}{Calories from Fat 10}\\
\NFRule
\NFline[r]{\% Daily Value*}\\
\NFrule
\NFelement{Total Fat}{1\,g}{2\%}\\
\NFrule
\NFelement{Sodium}{190\,mg}{8\%}\\
\NFrule
\NFelement{Total Carbohydrate}{2\,g}{1\%}\\
\NFrule
\NFelement{Protein}{1\,g}{}\\
\NFRule
\NFentry{Vitamin A 2\%}
\NFentry*{Vitamin C 15\%}\\
\NFentry{Iron 10\%}
\NFentry*{Vitamin B6 20\%}\\
\NFentry{Vitamin B12 4\%}\\
\NFrule
\NFtext{Not a significant source of saturated fat,
  trans fat, cholesterol, dietary fiber, sugars,
  and calcium.}\\
\NFrule
\NFtext{* Percent Daily Values are based on a
  2,000 calorie diet.}
\end{tabular}}
\end{document}

One possibility defining some auxiliary commands:

\documentclass{article}
\usepackage{graphicx}

\newcommand\myrule[1][1pt]{%
  \par\rule[1ex]{\linewidth}{#1}\par}

\newcommand\titlefont{\normalfont\Huge\bfseries}

\newcommand\Nline[3]{\textbf{#1}~#2\hfill#3\par}

\newcommand\Bullet[1]{\parbox{.5\linewidth}{\makebox[1em][l]{$\bullet$}#1}}

\newcommand\NutFact[3][8cm]{%
\par\noindent\resizebox{!}{#2}{\fbox{\begin{minipage}{#1}
\raggedright\sffamily
\vskip10pt
{\titlefont Nutrition Facts\par\medskip}
\large
#3
\end{minipage}}}%
}

\begin{document}

\NutFact{5cm}{%
Serving Size 2 tbsp. (33g) \par
Servings per Container 7\par
\myrule[9pt]
{\normalfont Amount per Serving\par}
\myrule
\Nline{Calories}{20}{Calories from Fat 10}
\myrule[6pt]
\hfill{\normalfont \% Daily Value\textsuperscript{*}\par}
\myrule
\Nline{Total Fat}{1g}{2\,\%}
\myrule
\Nline{Sodium}{190mg}{8\,\%}
\myrule
\Nline{Total Carbohydrate}{2g}{1\,\%}
\myrule
\Nline{Protein}{1g}{}
\myrule[11pt]
\Bullet{Vitamin A 10\,\%}%
\Bullet{Vitamin C 15\,\%}\par
\myrule
\Bullet{Iron 10\,\%}%
\Bullet{Vitamin B6 20\,\%}\par
\myrule
\Bullet{Vitamin B12 4\,\%}\par
\myrule
Not a significant source of satured fat, trans fat, cholesterol, dietary fiber, sugars, and calcium.
\myrule
\textsuperscript{*} Percent Daily Values are based on a 2,000 calorie diet.
}

\NutFact{4cm}{%
Serving Size 2 tbsp. (33g) \par
Servings per Container 7\par
\myrule[9pt]
{\normalfont Amount per Serving\par}
\myrule
\Nline{Calories}{20}{Calories from Fat 10}
\myrule[6pt]
\hfill{\normalfont \% Daily Value\textsuperscript{*}\par}
\myrule
\Nline{Total Fat}{1g}{2\,\%}
\myrule
\Nline{Sodium}{190mg}{8\,\%}
\myrule
\Nline{Total Carbohydrate}{2g}{1\,\%}
\myrule
\Nline{Protein}{1g}{}
\myrule[11pt]
\Bullet{Vitamin A 10\,\%}%
\Bullet{Vitamin C 15\,\%}\par
\myrule
\Bullet{Iron 10\,\%}%
\Bullet{Vitamin B6 20\,\%}\par
\myrule
\Bullet{Vitamin B12 4\,\%}\par
\myrule
Not a significant source of satured fat, trans fat, cholesterol, dietary fiber, sugars, and calcium.
\myrule
\textsuperscript{*} Percent Daily Values are based on a 2,000 calorie diet.
}

\end{document}

\NutFact has two mandatory arguments: the second one is the nutritional fact information, and the first one allows for some scaling; there's also an optional argument for the width of the inner minipage used.

With minipage you can do something.

Many other solution can do the job, e.g. with tabular

\documentclass{article}
\usepackage{siunitx}
\begin{document}


\begin{minipage}[h]{0.5\linewidth}
{\Large \bfseries Nutrition facts}

Serving Size tbsp. (\SI{33}{\gram})

Servings per container 7

\noindent\makebox[\linewidth]{\rule{\linewidth}{3pt}}

Amount per serving

\noindent\makebox[\linewidth]{\rule{\linewidth}{0.5pt}}

\textbf{Calories} \hfill Calories from Fat 10
\noindent\makebox[\linewidth]{\rule{\linewidth}{2pt}}

\flushright \% Daily Value \textsuperscript{*}

\noindent\makebox[\linewidth]{\rule{\linewidth}{0.5pt}}  
\flushleft
\textbf{Total Fat} \SI{1}{\gram} \hfill 2\%

\noindent\makebox[\linewidth]{\rule{\linewidth}{0.5pt}}

\textbf{Sodium} \SI{190}{\milli\gram}

\noindent\makebox[\linewidth]{\rule{\linewidth}{3pt}}
\begin{tabbing}
Vitamin A 2\% \quad \quad \= \textbullet\quad Vitamin C 15\%\\
Iron 10\% \> \textbullet \quad Vitamin B6 20\%
\end{tabbing}
\noindent\makebox[\linewidth]{\rule{\linewidth}{0.5pt}}
\footnotesize Not a significant source of saturated fat, trans
fat \ldots
\end{minipage}
\end{document}