\pounds and \textsterling produces a dollar sign?

As described in I've just been asked to write a minimal example, what is that? in such cases it is best to remove half of the used packages until the error disappears to track down the package which causes it. In your case the error seems to be caused by the iwona font. The wrong sign seems to be caused by the wrong font encoding. You should use \usepackage[T1]{fontenc} together with iwona to avoid such things.

This works:

\documentclass{article}

\usepackage[T1]{fontenc}
\usepackage[math]{iwona}
%\usepackage{amsmath,amsfonts}
%\usepackage{graphicx}
%\usepackage{algorithm,algorithmic}
%\usepackage{xspace}
%\usepackage{subfigure}
%\usepackage{url}
%\usepackage{lscape}
%\usepackage{listings}

\begin{document}

\pounds

\textsterling

\end{document}