A grid system is awesome to begin with to help with laying stuff out well. But this also includes some basic css boilerplate for typography, forms, tables, etc.
I would add CSS compilers like CleverCSS, SASS et al and CSS3 in the same timesaver category as grids. They make prototyping and iterating much faster with small and large projects.
Btw. Here's a nice CSS reset & typography to go with 960.gs and other grid systems http://borderleft.com/labs/
Yeah, using a grid-based css framework is a huge time saver. I find things tend to get a bit less readable when you've got "grid_5 alpha push_2 foo bar" classes everywhere, but hey, it does wonders for getting an MVP done.
Compass ( http://compass-style.org/ ) lets you use CSS frameworks while bypassing the problem of non-semantic class names by using SASS mixins. It's yet another layer of abstraction to learn, but worth a look if you don't know about it already.
http://www.designinfluences.com/fluid960gs/
A grid system is awesome to begin with to help with laying stuff out well. But this also includes some basic css boilerplate for typography, forms, tables, etc.
It's purposefully in black and white (see the grey box method http://v3.jasonsantamaria.com/archive//2004/05/24/grey_box_m...) which doesn't look half bad until you decide the mvp is worthy enough of some better style.