How can I add more than one logo to my beamer presentation?

Beamer provides \logo{} to set the logo(s). You could just add all three logos in there using three \includegraphics command (or PGF image commands). Where they are placed depends on your chosen scheme. If you want them a little larger on the title page you can insert the defined logo(s) manually \insertlogo e.g. inside a \scalebox.

The following code adds three scaled logos with one space as a separator into the right border. The default (blank) scheme puts them into the lower right corner.

\documentclass{beamer}

\author{Me}
\title{Presentation}
\logo{%
    \includegraphics[width=1cm,height=1cm,keepaspectratio]{logo1}~%
    \includegraphics[width=1cm,height=1cm,keepaspectratio]{logo2}~%
    \includegraphics[width=1cm,height=1cm,keepaspectratio]{logo3}%
}
\institute{Three Kings\\\scalebox{2}{\insertlogo}}
\begin{document}
\frame{\maketitle}
\frame{text}
\frame{}

\end{document}

you can have several logos on the page. The question is only where they should appear. Here an example for the second one in the sidebar.

\documentclass{beamer}
\usecolortheme{dove}
\useoutertheme{sidebar}
\pgfdeclareimage[height=2.25ex,width=2.5\baselineskip]{institut-logo}{zedat}
\pgfdeclareimage[height=1.3cm]{uni}{fu-berlin}
\logo{\pgfuseimage{uni}}
\setbeamertemplate{footline}{\raisebox{-2ex}{\pgfuseimage{institut-logo}}
  \usebeamerfont{date in head/foot}\insertshortdate{}\hfill
  \usebeamertemplate{navigation symbols}\hfill
  \insertframenumber{}/\inserttotalframenumber}
\setbeamertemplate{sidebar right}{}

\begin{document}
\begin{frame}{Das Logo}
\begin{block}{Ein Beispiel mit der Umgebung \texttt{block}}
Es ist offensichtlich, dass wir hier zwei Logos auf der Folie haben.
\end{block}
\end{frame}
\end{document}

from: http://tex.stackexchange.com/questions/18410/how-can-i-add-more-than-one-logo-to-my-beamer-presentation

Logo in Latex Beamer Presentation / Slideshow

• The logo is on the bottom right corner of every page: to do that use the \logo command. Here's a complete code example:

\documentclass[compress]{beamer}
\usepackage[latin1]{inputenc}
\usepackage{pgf,pgfarrows,pgfnodes,pgfautomata,pgfheaps,pgfshade}
\usepackage{amsmath,amssymb}
\usepackage[latin1]{inputenc}
\usepackage{colortbl}
\usepackage{graphicx}
\usepackage[english]{babel}
\usepackage{tabularx}
\usetheme{Singapore}%define the beamer theme
\setbeamertemplate{navigation symbols}{}%remove navigation symbols\setbeamertemplate{section in head/foot shaded}[default][20]\setbeamertemplate{subsection in head/foot shaded}[default][20]
\logo{\includegraphics[height=0.5cm]{youlogoname.eps}} %change here. I used an eps file logo, you can use jpg or other format
\title[My Title ]{My~Title}
\author[My~Name]{My~Name}
\institute[My Institute/company]{My Institute/company\\ \date[DLT 2007]{My Seminar name/place/date}
\subject{My title/subejct}
\begin{document}
Type document content here
\end{document}

• The logo is only on the front page: use \pgfdeclareimage and\pgfuseimage. Here's teh example:

\documentclass[compress]{beamer}
\usepackage[latin1]{inputenc}
\usepackage{pgf,pgfarrows,pgfnodes,pgfautomata,pgfheaps,pgfshade}
\usepackage{amsmath,amssymb}
\usepackage[latin1]{inputenc}
\usepackage{colortbl}
\usepackage{graphicx}
\usepackage[english]{babel}
\usepackage{tabularx}
\usetheme{Singapore}%define the beamer theme
\setbeamertemplate{navigation symbols}{}%remove navigation symbols
\setbeamertemplate{section in head/foot shaded}[default][20]
\setbeamertemplate{subsection in head/foot shaded}[default][20]
\title[My Title ]{My~Title} \author[My~Name]{My~Name}
\institute[My Institute/company]{My Institute/company\\ \pgfdeclareimage[height=0.5cm]{myalias}{pselogo} %declare logo image with an alias here \pgfuseimage{myalias}} %use the image right after
\date[DLT 2007]{My Seminar name/place/date} \subject{My title/subejct}
\begin{document}
Type document content here
\end{document}

from: http://stuffforlife.blogspot.ca/2008/10/logo-in-latex-beamer-presentation.html