\documentclass{article}
\usepackage[landscape]{geometry}% http://ctan.org/pkg/geometry
\usepackage{array}% http://ctan.org/pkg/array
\usepackage{rotating}
\usepackage{makecell}

\begin{document}

% =========== multi-line cells ===========

	\begin{center}
		\begin{tabular}{ | c | c | c |}
			\hline
			\thead{A Head} & \thead{A Second \\ Head} & \thead{A Third \\ Head} \\
			\hline
			Some text &  \makecell[l]{Some really \\ longer text}  & Text text text  \\
			\hline
		\end{tabular}
	\end{center}

% =========== FACTOR approach ===========
{\renewcommand{\arraystretch}{2}%
\begin{tabular}{|l|l|}
  \hline
  column 1 & column 2 \\
  \hline
  I really would like this less & crammed \\
  \hline
\end{tabular}} \quad
% =========== LENGTH approaches ===========
\begin{tabular}{|l|l|}
  \hline
  column 1 & column 2 \\[4ex]
  \hline
  I really would like this less & crammed \\[5pt]
  \hline
\end{tabular} \quad
{\setlength{\extrarowheight}{20pt}%
\begin{tabular}{|l|l|}
  \hline
  column 1 & column 2 \\
  \hline
  I really would like this less & crammed \\
  \hline
\end{tabular}}

% vertical text in table cells

\begin{tabular}{|c|c|}
 \begin{sideways} column 1 \end{sideways} & col 2 \\ \hline
  text, requires rotating package & text2 \\
\end{tabular}

\begin{table}

% text wrapping in table cells

\begin{tabular}{|l|c|}
 
 \hline
 col a & col b \\ \hline

 tensor &  \parbox{12cm}{\vskip 1mm
  \begin{itemize}
   \item Tensors are geometric objects that describe linear relations between vectors, scalars, and other tensors. Elementary examples of such relations include the dot product, the cross product, and linear maps. Vectors and scalars themselves are also tensors. A tensor can be represented as a multi-dimensional array of numerical values. The order (also degree) of a tensor is the dimensionality of the array needed to represent it, or equivalently, the number of indices needed to label a component of that array. For example, a linear map can be represented by a matrix (a 2-dimensional array) and therefore is a 2nd-order tensor. A vector can be represented as a 1-dimensional array and is a 1st-order tensor. Scalars are single numbers and are thus 0th-order tensors. It is very important not to confuse dimensions of the array with dimensions of the underlying vector space.
  \end{itemize}
 } \\ \hline

 inductive reasoning &  \parbox{12cm}{\vskip 1mm
  \begin{itemize}
   \item Inductive reasoning (as opposed to deductive reasoning) is reasoning in which the premises seek to supply strong evidence for (not absolute proof of) the truth of the conclusion. While the conclusion of a deductive argument is supposed to be certain, the truth of the conclusion of an inductive argument is supposed to be probable, based upon the evidence given.
  \end{itemize}
 } \\ \hline

\end{tabular}  

\caption{Text wrapping in table cells.}
\end{table}

% histogram kind of bars in table cells; copied from our IJAR paper

\begin{table}[tbh]
  \setlength{\tabcolsep}{1pt}
  \centering
  {\small
  \begin{tabular}{|r|ccc|ccccc|cccccc|cccc|c|}\hline
 & \multicolumn{3}{c|}{Observations}
 & \multicolumn{5}{c|}{Task}
 & \multicolumn{6}{c|}{Behaviour}
 & \multicolumn{4}{c|}{Ability}
 & \\ \cline{2-19}
 \begin{sideways}Time step, t\end{sideways}
  & \begin{sideways}brush\_wet\end{sideways}
  & \begin{sideways}tap\end{sideways}
  & \begin{sideways}brush\_position\end{sideways}
  & \begin{sideways}brush\_wet\end{sideways}
  & \begin{sideways}brush\_in\_hand\end{sideways}
  & \begin{sideways}brush\_in\_cup\end{sideways}
  & \begin{sideways}brush\_on\_surface\end{sideways}
  & \begin{sideways}tap\_on\end{sideways}
  & \begin{sideways}other\end{sideways}
  & \begin{sideways}nothing\end{sideways}
  & \begin{sideways}alter\_tap\_to\_on\end{sideways}
  & \begin{sideways}take\_brush\_from\_cup\end{sideways}
  & \begin{sideways}wet\_brush\end{sideways}
  & \begin{sideways}take\_brush\_from\_surface\end{sideways}
  & \begin{sideways}Rn\_brush\_in\_cup\end{sideways}
  & \begin{sideways}Rn\_brush\_on\_surface\end{sideways}
  & \begin{sideways}Af\_tap\end{sideways}
  & \begin{sideways}Af\_water\end{sideways}
  & \begin{sideways}\makecell{System Action\\(prompt for ability specified)}\end{sideways}
\\ \hline
 0
 & dry 
 & off 
 & in\_cup 
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{0.20mm}
 & \rule{3mm}{1.20mm}
 & \rule{3mm}{0.60mm}
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{1.90mm}
 & \rule{3mm}{1.90mm}
 & \rule{3mm}{1.60mm}
 & \rule{3mm}{1.60mm}
 & Af\_tap 
\\ \hline
 1
 & dry 
 & off 
 & in\_cup 
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{0.14mm}
 & \rule{3mm}{1.82mm}
 & \rule{3mm}{0.06mm}
 & \rule{3mm}{0.08mm}
 & \rule{3mm}{0.40mm}
 & \rule{3mm}{0.64mm}
 & \rule{3mm}{0.08mm}
 & \rule{3mm}{0.08mm}
 & \rule{3mm}{0.40mm}
 & \rule{3mm}{0.40mm}
 & \rule{3mm}{1.62mm}
 & \rule{3mm}{1.76mm}
 & \rule{3mm}{1.96mm}
 & \rule{3mm}{1.44mm}
 & Af\_tap 
\\ \hline
 2
 & dry 
 & off 
 & in\_cup 
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{0.04mm}
 & \rule{3mm}{1.96mm}
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{0.04mm}
 & \rule{3mm}{0.36mm}
 & \rule{3mm}{0.82mm}
 & \rule{3mm}{0.04mm}
 & \rule{3mm}{0.04mm}
 & \rule{3mm}{0.36mm}
 & \rule{3mm}{0.36mm}
 & \rule{3mm}{1.50mm}
 & \rule{3mm}{1.70mm}
 & \rule{3mm}{2.00mm}
 & \rule{3mm}{1.38mm}
 & Rn\_brush\_cup 
\\ \hline
 3
 & dry 
 & off 
 & in\_hand 
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{1.78mm}
 & \rule{3mm}{0.22mm}
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{0.02mm}
 & \rule{3mm}{0.04mm}
 & \rule{3mm}{0.14mm}
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{1.74mm}
 & \rule{3mm}{0.04mm}
 & \rule{3mm}{0.04mm}
 & \rule{3mm}{2.00mm}
 & \rule{3mm}{1.68mm}
 & \rule{3mm}{1.62mm}
 & \rule{3mm}{1.36mm}
 & Af\_tap 
\\ \hline
 4
 & dry 
 & on 
 & in\_hand 
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{2.00mm}
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{1.88mm}
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{1.88mm}
 & \rule{3mm}{0.12mm}
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{1.80mm}
 & \rule{3mm}{1.68mm}
 & \rule{3mm}{2.00mm}
 & \rule{3mm}{1.34mm}
 & Af\_water 
\\ \hline
 5
 & dry 
 & on 
 & in\_hand 
 & \rule{3mm}{0.08mm}
 & \rule{3mm}{2.00mm}
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{2.00mm}
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{0.06mm}
 & \rule{3mm}{1.80mm}
 & \rule{3mm}{0.04mm}
 & \rule{3mm}{0.10mm}
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{1.72mm}
 & \rule{3mm}{1.68mm}
 & \rule{3mm}{1.62mm}
 & \rule{3mm}{1.94mm}
 & Af\_water 
\\ \hline
 6
 & wet 
 & on 
 & in\_hand 
 & \rule{3mm}{1.90mm}
 & \rule{3mm}{2.00mm}
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{2.00mm}
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{0.06mm}
 & \rule{3mm}{0.08mm}
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{1.84mm}
 & \rule{3mm}{0.01mm}
 & \rule{3mm}{1.68mm}
 & \rule{3mm}{1.66mm}
 & \rule{3mm}{1.44mm}
 & \rule{3mm}{2.00mm}
 & donothing 
\\ \hline
  \end{tabular}
  }
  \caption{Requires package makecell}
  \label{TAB:TOOTHRESULTS}
\end{table}


\end{document}