I second Brandon's suggestion to use a CSS framework. It won't give you 100% freedom to design anything you like, but it can speed up your design process greatly and free up your hands to do the coding you really want.
Suggestions Updated July 2013:
- Twitter Bootstrap http://twitter.github.io/bootstrap/ - complete grid, typo, UI widget prototyping framework
- ZURB Foundation http://foundation.zurb.com/ - responsive grid, type, UI widget prototyping framework (similar in scope to Twitter Bootstrap, but feels 'cleaner' in some ways)
- 960 http://960.gs/ - grid layout system
- Tripoli http://devkick.com/lab/tripoli/ - really good typography, but no grid system
- YUI Grids http://developer.yahoo.com/yui/grids/ - very customizable (to the point of overkill) grid system
- Blueprint http://www.blueprintcss.org/ - grid system and basic typography
- BlueTrip http://www.bluetrip.org - a hybrid system, mixing the best of the Blueprint grid with the best of the Tripoli typography