I have to admit that when I got my SGS4 I was rather excited about it's wireless charging abilities. I have the Frost white SGS4 with the S-View back plate and cover. Let me start of by saying I LOVE my S-View cover. I picked up a Nokia inductance charging pad from my office, brought it home and eagerly put my S4 on the pad; boy was I disappointed. After 5-10 times of picking my phone up and putting it back down, all with no pretty little charge LED coming on, I realized something wasn't right. I immediately hopped and Google and realized that my shiny new S4 was "wireless charging capable", not wireless charging equipped. I have several friends who made the same mistake, so don't feel bad if you did. In fact, I personally believe that Samsung may have been just a little deceptive with their marketing, but that's a story for another day.
Anyhow, I set out to find a solution to my problem and stumbled upon the "Wireless Charger Receiver Module" by Qi. I got mine of Amazon for about $12. That's a pretty cheap price in my humble opinion to add wireless charging support. The Qi pad essentially gets placed on the back of the battery in such a way that the two contacts touch the two charging terminals on the back of the phone. It has a small 3M sticky strip you pull off to make it more permanent. Once that's done, just put your back-plate back on, and you are ready to go. If you go looking for this gem make sure you get the one for the S4. The Internet is littered with the charging pads for the S3's and it's sometimes difficult to get the right one. The one for the S3 may or may not work, I won't be the girl trying it!
Tip: I found that the easiest way to align the charging pad on the battery is to put the battery in the phone, place the contacts against the pads, and then remove the tap and stick it to the battery. I have included a few pics for you.