http://www.whsmith.co.uk/eBooks/FreeeBooks.aspx (http://www.whsmith.co.uk/eBooks/FreeeBooks.aspx)
and for a very large list;
http://www.techsupportalert.com/content/free-epub-books-online.htm (http://www.techsupportalert.com/content/free-epub-books-online.htm)