Using a CSS reset has saved me a lot of time and frustration with cross-browser styling. It is annoying however that most reset style scripts reset every element in the html spec...most of which you'll likely never use on your project. Tuhin over at Inspiring Pixel wrote a good post on the pros and cons to using a css reset, and also provides a bunch of different reset scripts based on your needs. I'll definitely be referencing this for future projects.
This makes me wonder though, is there a tool out there that can generate a reset script for you based on the elements you know you'll be using on your project? If not maybe I'll go build one.