Our heritage as Christians includes visual elements: stained glass, liturgical colors, the sacraments as visible signs, church architecture, sermon illustrations. Many of these were about contextualization.
Sermon Painting 101: replace every place where you’d have a bullet point with an image. Communion is a great example of a five-sense experience. Sermon painting is not for everyone: it takes more time to prepare, and it’s harder to preach this way.
Some good resources for images: stock.xchng, Wikimedia Commons, Google Images. iStockPhoto is a good source if you have to pay. There are also personal resources: your friends might have images, or be able to track things down for you. Join the “Sermon Painting” group on Facebook. You can use open source tools for the image editing.