Don’t use XML- 1 min
Knowing about computer languages and language technology such as ANTLR will make your coding life much easier. Don’t be afraid to build a human-readable configuration file (I implore everyone to please stop using XML as a human interface!) or to build domain specific languages to make yourself more efficient. Designing new languages, when appropriate, is the hallmark of a sophisticated developer.
Terence Parr, in his ANTLR book.
To develop an external DSL can be fun if you have a great tool like ANTLR in hands.