This is a sort-of-working version of a LaTeX class I'm working on for typesetting conference programmes.

conference.cls

  %% conference.cls
  %% Copyright 2014 Seamus Bradley
  %
  % This work may be distributed and/or modified under the
  % conditions of the LaTeX Project Public License, either version 1.3
  % of this license or (at your option) any later version.
  % The latest version of this license is in
  %   http://www.latex-project.org/lppl.txt
  % and version 1.3 or later is part of all distributions of LaTeX
  % version 2005/12/01 or later.
  %
  % This work has the LPPL maintenance status `author-maintained'.
  % 
  % The Current Maintainer of this work is Seamus Bradley
  % tex@seamusbradley.net
  %
  % This work consists of the files conference.cls
  % and README.


\RequirePackage{expl3}
\ProvidesExplClass{conference}{2013/05/13}{0.2}{Conference Schedule Class}

\LoadClass[fontsize=11pt,]{scrartcl}
%\LoadClassWithOptions{article}[12pt]

\RequirePackage{xparse,l3sort,multirow,typearea,hyperref,tabularx,array}

\areaset{160mm}{270mm}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Title set up
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% We set up a property list that holds all the relevant information for the title block
\prop_new:N \g_titleblock_prop

% We generate some document commands that allow the user to set the parts of the title block

\NewDocumentCommand{\SetTitle}{m}{
  \prop_gput:Nnn \g_titleblock_prop {title} {#1}
}

\NewDocumentCommand{\SetInstitute}{m}{
  \prop_gput:Nnn \g_titleblock_prop {institute} {#1}
}

\NewDocumentCommand{\SetDates}{m}{
  \prop_gput:Nnn \g_titleblock_prop {dates} {#1}
}

\NewDocumentCommand{\SetWebsite}{m}{
  \prop_gput:Nnn \g_titleblock_prop {website} {#1}
}

\NewDocumentCommand{\SetVenue}{m}{
  \prop_gput:Nnn \g_titleblock_prop {venue} {#1}
}

% Finally, we define a document command to print the title block.
% Currently, rather crude.

\NewDocumentCommand{\MakeTitle}{}{
  \begin{center}
    {\Large \bfseries \prop_get:Nn \g_titleblock_prop {title} }\\[1em]
    {\large\itshape \prop_get:Nn \g_titleblock_prop {institute} }\\[1em]
    {\url{\prop_get:Nn \g_titleblock_prop {website} }}\\[1em]
    {\itshape \prop_get:Nn \g_titleblock_prop {venue} }
  \end{center}
}


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Setup
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% We setup a sequence that holds the sort names (defined by the first option of the \AddTalk macro).
% We also need a variable that holds the current date.

\seq_new:N \g_names_seq
\tl_new:N \l_thedate_tl
\tl_new:N \l_tmpnote_tl
\tl_new:N \l_thetime_tl

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% The AddTalk macro
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% Time, Name, Title

% Sort, Name, Title, Abstract
\NewDocumentCommand{\AddTalk}{mmm+m o}{
  \prop_new:c {g_#1_prop}
  \prop_gput:cnn {g_#1_prop} {name} {#2}
  \prop_gput:cnn {g_#1_prop} {title} {#3}
  \prop_gput:cnn {g_#1_prop} {abstract} {#4}
  \seq_gput_right:Nn \g_names_seq {#1}
  \IfNoValueTF{#5}{
  }{
    \prop_gput:cnn {g_#1_prop} {note} {#5}
  }
}

% \NewDocumentCommand{\ConferenceBreak}{mm}{
%   && \\
%   \emph{#1} &
%   \multicolumn{2}{c}{
%     \textbf{#2}\hspace*{5em}
% }
% \\
% &&\\
% }

%   

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Timing
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\int_new:N \l_timing_tmp_hour
\int_new:N \l_timing_tmp_min
\int_new:N \l_timing_tmp_min_inc
\int_new:N \l_timing_tmp_hour_inc

\tl_new:N \l_timing_tmp_return

\prop_new:N \timing_mytime

\cs_new:Npn \timing_new_time:n #1 {
  \prop_new:c {timing_#1_time}
  \prop_gput:cnn {timing_#1_time}{hour}{0}
  \prop_gput:cnn {timing_#1_time}{minute}{0}  
}

\cs_new:Npn \timing_set_time:nnn #1#2#3 {
  \prop_gput:cnn {timing_#1_time}{hour}{#2}
  \prop_gput:cnn {timing_#1_time}{minute}{#3}
}

\cs_new:Npn \timing_return_time:n #1 {
  \tl_set:Nx \l_timing_tmp_return {
    \int_compare:nNnTF {\prop_get:cn{timing_#1_time}{hour}} < {10} {0}{}
    \prop_get:cn {timing_#1_time}{hour}:
    \int_compare:nNnTF {\prop_get:cn{timing_#1_time}{minute}} < {10} {0}{}
    \prop_get:cn {timing_#1_time}{minute}
  }
%  \tl_show:N \l_timing_tmp_return
  \l_timing_tmp_return
}

\cs_new:Npn \timing_add_time:nn #1#2{
  \int_set_eq:NN \l_timing_tmp_hour \prop_get:cn{timing_#1_time}{hour}
  \int_set_eq:NN \l_timing_tmp_min \prop_get:cn{timing_#1_time}{minute}
  \int_set:Nn \l_timing_tmp_hour_inc {\int_div_truncate:nn {\l_timing_tmp_min + #2}{60}}
  \int_set:Nn \l_timing_tmp_min_inc {\int_mod:nn {\l_timing_tmp_min +#2}{60}}
  \int_set:Nn \l_tmpa_int    {\int_eval:n {\l_timing_tmp_hour + \l_timing_tmp_hour_inc}}
  \prop_gput:cnV{timing_#1_time} {hour} \l_tmpa_int
  \int_set:Nn \l_tmpa_int {    \int_eval:n {\l_timing_tmp_min_inc} }
  \prop_gput:cnV{timing_#1_time} {minute} \l_tmpa_int
}


\cs_new_protected:Npn \timing_store_time:nn #1#2 {
  % name, increment
  \tl_gset:Nn \l_thetime_tl {
    \timing_return_time:n{conf} --
    \timing_add_time:nn{conf}{#2}
    \timing_return_time:n{conf}
  }
  \prop_gput:cnV {g_#1_prop} {time} {\l_thetime_tl}
}

\NewDocumentCommand{\NewTime}{m}{
  \timing_new_time:n{#1}
}

\NewDocumentCommand{\SetTime}{mmm}{
  \timing_set_time:nnn{#1}{#2}{#3}
}

\NewDocumentCommand{\PrintTime}{m}{
  \timing_return_time:n{#1}
}

\NewDocumentCommand{\AddTime}{mm}{
  \timing_add_time:nn {#1}{#2}
}


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% The Day environment
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\setlength\extrarowheight{0.4em}
\NewTime{conf}

\NewDocumentEnvironment{Day}{mmm}{
% Parameters: Date, Start hour, Start minute
  \tl_set:Nn \l_thedate_tl {#1}
  \SetTime{conf}{#2}{#3}
  \begin{center}
    \textbf{#1}
  \end{center}
  \begin{tabular}{l>{\raggedright}p{18em}p{20em}}
}{
    \end{tabular}
}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% The UseTalk command
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% \NewDocumentCommand{\PrintTalk}{mmmm}{
%   \emph{#1} &  \textbf{#2} &  #3  \\
% }


\NewDocumentCommand{\UseTalk}{mm}{
  \prop_gput:cnV {g_#1_prop} {date} {\l_thedate_tl}
  \timing_store_time:nn{g_#1_prop}{#2}
  % \tl_set:Nn \l_thetime_tl {
  %   \timing_return_time:n{conf} --
  %   \timing_add_time:nn{conf}{#2}
  %   \timing_return_time:n{conf}
  % }
  % \prop_gput:cnV {g_#1_prop} {time} {\l_thetime_tl}
  \prop_show:c {g_#1_prop}
  \emph{\l_thetime_tl} & \textbf{\prop_get:cn {g_#1_prop}{name}} & \prop_get:cn{g_#1_prop}{title} \\
}

\NewDocumentCommand{\ConferenceBreak}{mm}{
  && \\
  \tl_set:Nn \l_thetime_tl {
    \timing_return_time:n{conf} --
    \timing_add_time:nn{conf}{#2}
    \timing_return_time:n{conf}
  }
  \emph{\l_thetime_tl} &
  \multicolumn{2}{c}{
    \textbf{#1}\hspace*{5em}
}
\\
&&\\
}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% The PrintAbstract command
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\NewDocumentCommand{\PrintAbstract}{m}{
  \hspace{-2em}
  \textbf{\prop_get:cn {g_#1_prop} {title}},~
  \emph{\prop_get:cn {g_#1_prop} {name}},~
  \prop_get:cn {g_#1_prop} {date},~ 
  \prop_get:cn {g_#1_prop} {time}.~
  \prop_get:cnNTF {g_#1_prop} {note} \l_tmpa_tl {\emph{[\tl_use:N \l_tmpa_tl]}.~}{}
  \prop_get:cn {g_#1_prop} {abstract}\\[1em]\par
}

\NewDocumentCommand{\ListAbstracts}{}{
  \begin{center}
    \textbf{Abstracts}
  \end{center}

  \setlength\parindent{0pt}
  \seq_map_inline:Nn \g_names_seq {\PrintAbstract{##1}}
}

%%%%%%%%% Testfile:
% \documentclass{conference}

% \begin{document}

% \AddTalk{foo}{Name foo}{Title foo}{Abstract foo}

% \AddTalk{bar}{Name bar}{Title bar}{Abstract bar}

% \begin{Day}{14 May}{9}{30}
%   \UseTalk{foo}{45}

% \UseTalk{bar}{45}
% \end{Day}

% \ListAbstracts
% \end{document}