Girolamo Francesco Maria Mazzola, more commonly known as Parmigianino - Self-Portrait in a Convex Mirror:
http://www.1st-art-gallery.com/thumbnail/93046/1/Self-Portrait-In-A-Convex-Mirror-C.-1524.jpg
MC Escher - Hand with Reflecting Sphere:
http://myhero.com/images/Artist/Escher/g1_u28675_HandWithReflectingSphere.jpg
Diego Velazquez - Las Meninas:
http://artchive.com/graphics/meninas.jpg
Please note that Velazquez paints himself in the mirror, and the mirror of the king and queen are in the mirror in the background. The queen may have been pregnant at the time, so it would have been inappropriate to paint her picture in the normal fashion.
Jan Van Eyck - Arnolfini Wedding
http://www.artinthepicture.com/paintings/Jan_van_Eyck/The-Arnolfini-Wedding/
Portrayed self in mirror in background
Phil Douglas - Past meets Present (Photograph):
http://thump01.pbase.com/g6/82/265582/3/80831788.F9hYAQc9.jpg
Titian - Venus With a Mirror:
http://www.artchive.com/artchive/t/titian/titian_venus_mirror.jpg
Caravaggio - Narcissus
http://www.canvasreplicas.com/images/Narcissus%20Caravaggio.jpg
Here are a few:
http://darlingpicky.blogspot.com/2009/02/planar-mirror-flatperfect-reflection.html
Manet - A Bar at the Folies-Bergère:
http://4.bp.blogspot.com/_FaKp7qyZQuw/TFFNvqaybEI/AAAAAAAAAEg/_TarlX0YvlE/s1600/manet.jpg
Picasso - Girl Before a Mirror:
http://www.abcgallery.com/P/picasso/picasso258.html
You may consider reflections in water, spoons, tea kettles, windows, etc.
Hope I could help!