This is a presentation I gave at the recent CharityComms Digital Impact Conference in London.
My research shows that over 60% of visitors to UK charity sites, dedicated to causes, come from Organic search and site wide Bounce Rates of 60% are not uncommon. So improving your site for search engine results ( read-Google) will give a significant increase in satisfied visitors without the need for any additional marketing. To show the effects of a generally poor site experience, including a high Bounce Rate, I imagine your site as a Department Store where 60% of people who enter leave very quickly. This presentation shows what you can do to help many more of your current visitors find what they came for. The presentation also covers some other aspects of search in general, including AdWords and looks at keyword selection and analysis.
You can see some of the audience reaction at Twitter #charitydigital and you will find some additional info and links in my Twitter feed @find50.