NiCAD or NiCD or Nicke Cadmium Batteries come in all the standard sizes from AAA to D. You can use them to power all your kid's electronic toys and the batteries will last longer than the regular Duracell and Energizer batteries you buy at the local grocery or wholesale store.  You can save hundreds of dollars by not having to buy new batteries all the time and your kids will have even more fun and get more use out of all the toys they get every birthday and Christmas. 

Here's what Wikipedia says about the NiCAD batteries:

"With a relatively low internal resistance, a NiCd battery can supply high surge currents. This makes them a favorable choice for remote-controlled electric model aeroplanes, boats, and cars, as well as cordless power tools and camera flash units."

So you can use them and recharge them hundreds of times for your remote control cars, planes, boats, and other high surge devices.  You can spend a few dollars for each at your local store or you can buy rechargeable NiCAD batteries online for much less.  Many of the offers come with free shipping now so your costs are even lower.

Shop now for discount NiCAD batteries

So now you know you can buy NiCAD batteries cheaper online than at your local store.  But that is not all there is to know.  You need to know a little bit about the capacity of the batteries you intend to buy.  The higher the capacity the better.  This will give you a longer battery life so you don't have to recharge them as often. Look for 800-1000 mAh capacity or larger. You'll get more play out of your batteries with the higher capacity.

You do not have to buy name brand batteries like Sony or other manufactures.  You can buy reliable brands on eBay for much less than the 'name brand' batteries you always see in the store. If you are going to be using 8, 10, 12 batteries for all your devices all the time, get a bigger battery charger so you can charge all your batteries at once instead of only 4 at a time.

This way you're not fighting over who gets to play with what because you only have a few NiCAD batteries charged.