Wiping a steamed up bathroom mirror with your hand can be grounds for divorce.
The Clear Mirror electrical mirror defogger could save your marriage. This is an electrical pad with self adhesive backing that glues to the back of your mirror. You tie a transformer into the bathroom light to power it, and every time you turn on your bathroom light, there is 30 watts of heat on a portion of your mirror, just enough to keep it fog free. That means that someone can shave or put on make-up while someone else is taking a shower. Now that's marital bliss! The first photo shows the heater being placed on the back of the mirror. Look closely at the second photo to see the clear section of the mirror. I first saw one of these in a fancy hotel and searched for years to locate a supplier. Then it showed up at a hardware show but they are still hard to find around the country. I've installed several and recommend them to all couples. For more information follow this link to "ClearMirror.com".
Remember that all electrical work requires a permit, some provinces allow homeowners to do their own electrical work and some provinces require licensed electricians to carry out all such work. Also, neither transformers nor junction boxes can be buried into walls where you do not have access to them for heat displacement and repair. So if you can't put the transformer right in the medicine cabinet, drop a line from the light junction box to under the counter where you can install a proper junction box and the transformer. Click here for information on the LEGALITY OF DIY ELECTRICAL WORK.