Infrared LEDs are awesome. Along with an IR receiver they can be used for remote control and even basic remote data communication. The only problem is that your Arduino won't drive them to their full potential. The Max Power IR LED kit solves this problem by providing you with everything you need to drive a 950nm IR LED properly. Simply solder together this easy through-hole kit and you can switch the LED using a transistor.
Once the kit is assembled, simply provide it with voltage (5V), ground, and connect the CTL pin to a digital pin on your Arduino, and you can drive this kit just like a normal LED. Although the LED won't be visible to your naked eye, you can use a video camera, cell phone camera, or digital camera to see if the LED is working properly.
Note: We made a design mistake with this board and so it doesn't quite reach the 50mA maximum current that the LED is rated for. However, we are still measuring about 48mA through the LED which seems to work quite well.