One complaint I've heard about "real" soap is that it tends to get a little slimy if it sits in a puddle of water. It seems that a lot of soap dishes are made just to look nice and function is overlooked entirely. Soap mats are the best solution I have found to avoid that melty, gooey effect and to dry the soap between uses, making it last longer. You can either rest it in your current soap dish or use it instead of a soap dish. Whenever it starts looking a little soapy, just wash it along with your towels and such.
Mine measure about 4"x 3". I've become adept at crocheting in the car or in front of a movie and can make them fairly quickly. I even make them during slow times at craft shows. As a matter of fact, these usually sell rapidly at craft shows so I restock on the spot. It's incredible how many people don't even have soap dishes these days (gasp).