I've started to learn about using a speedlight (flash de mano) with my camara. I've bought myself the Nikon Autofocus Speedlight SB-600. I invested in this flash for two reasons:
1. It is compatible with both my digital and film camera.
2. It can be used in both Manual and TTL mode.
The built-in flash on digital SLR camera's works for most situations but it's has less reach and doesn't lend itself for more creative lighting scenarios.