A quote I came across a while back (sorry, I can't recall who said it) is "There are only two difficult problems in software development - cache invalidation and naming things". For me, one of the biggest productivity boosts in a development environment is the ability to easily re-name things. This stops me from spending too much time up-front trying to decide on the ideal name for something, knowing that I can change it easily as the code progresses and I understand the concept I am trying to express more clearly.