Something like this?
\documentclass{article}
\usepackage{multicol}
\usepackage{enumitem}
\begin{document}
\begin{multicols}{3}
\begin{enumerate}[label={\arabic*)}]
\item
\item
\item
\item
\item
\item
\item
\item
\item
\item
\item
\item
\item
\item
\item
\item
\item
\item
\item
\item
\item
\item
\item
\item
\item
\item
\item
\item
\item
\end{enumerate}
\end{multicols}
\end{document}

The special Alenanno - Version:
\documentclass{article}
\usepackage{multicol}
\usepackage{etoolbox}
\listadd{\mywhitespacelist}{}%
\forcsvlist{\listadd\mywhitespacelist}{This,is,a,very,long,text,split,in,many,many,many,useless,separate,item,which,is,extended,just,because,Alenanno,wants,to,have,more,than,thirty,items,in,here,but,he,did,not,explain,why,this,is,the,case,so,who,cares?}
\usepackage{enumitem}
\begin{document}
\begin{multicols}{3}
\begin{enumerate}[label={\arabic*)}]
\renewcommand*{\do}[1]{%
\item \textbf{#1}
}%
\dolistloop{\mywhitespacelist}
\end{enumerate}
\end{multicols}
\end{document}

\usepackage{multicol}and in the body\begin{multicols}{3} your list \end{multicols}should do – Jun 22 '15 at 12:44