As far as tools go, Ive found browsershots and Litmus app helpful and of course, vm's as well for checking things out live in ie-{6,7,8}. Otherwise I do the heavy lifting in vim.
For generating new markup thats not tied to a target design I think some of the css frameworks & tools like sass look useful but Im skeptical of their utility when needing to generate markup to match a photoshop design. Am I wrong?
So what tips / tools do you keep in your markup generating utility belt when building solid markup from designs?