Consolas is my favorite monospace font. It’s a good programmer’s font because it exaggerates the differences between some characters that may easily be confused. It ships with Visual Studio and with many other Microsoft products. See this post for examples.
Andika is a sans serif, Unicode-compliant font designed especially for literacy use, taking into account the needs of beginning readers. The focus is on clear, easy-to-perceive letterforms that will not be readily confused with one another.