If you are looking for some great free graphics that highlight words in a range of formats, then Blue Diamond Gallery is an easy-to-use free program. There is an A-Z list of words you can choose from in each of the three graphic styles: Dictionary Pictures, Tablet Words and Wooden Tile Word Pictures. Once you have selected the style and word you need, you are provided with details of the author and attribution rights, meaning the picture can be copied, saved, and redistributed freely.
There are also purchasing options available if you wish to purchase higher-resolution pictures at a larger size. For educational purposes, this website is an excellent introduction into thinking about the visual placement of titles and words, with the resource also being a a great model for what students could create themselves.