Coding VBA with VBA.
The idea of writing code that writes code has a certain coolness about it. Being able to give your application the ability to recode itself is part and parcel to AI techniques of coding intelligence because essentially your application can grow and learn. There are many specialised languages that have been designed with this in mind, Lisp for example, but you wouldn't really classify VBA as one of these languages however the ability for VBA to rewrite itself is there and the article at the link below covers, in good detail, how to do it.
http://www.cpearson.com/excel/vbe.htm