This is an example which corresponds to my "Getting Started" blog post: Getting Started with nRF24L01+ on Arduino.

It is an example of how to use the RF24 class. Write this sketch to two different nodes. Put one of the nodes into 'transmit' mode by connecting with the serial monitor and sending a 'T'. The ping node sends the current time to the pong node, which responds by sending the value back. The ping node can then see how long the whole cycle took.