C# - using keyword
Most devs I work with are shocked to learn that the using keyword in the C# language is diatic. The obvious is for namespace inclusion but the less often seen use is for aliasing. For example, I hate having to reference the static members of ConfigurationSettings via the fully qualified name of System.Configuration.ConfigurationSettings. This is where aliasing can be cool; just give the class an alias with the using keyword like this:
using cfg = System.Configuration.ConfigurationSettings;
This will allow you to refer to the members of System.Configuration.ConfigurationSettings using the cfg alias name.