I've been thinking about 'what is creativity', and a good a place as any seemed to be Wikipedia:
Creativity (or "creativeness") is a mental process involving the generation of new ideas or concepts, or new associations between existing ideas or concepts.
According to Dictionary.com, creativity is:
the ability to transcend traditional ideas, rules, patterns, relationships, or the like, and to create meaningful new ideas, forms, methods, interpretations, etc.; originality, progressiveness, or imagination: the need for creativity in modern industry; creativity in the performing arts.