Twitter bootstrap fluid grid system works with percentages : http://twitter.github.com/bootstrap/scaffolding.html#fluidGridSystem
There is also a lot of pure css responsive grid system, for exemple : Skeleton
This article covers a lot of them : http://speckyboy.com/2011/11/17/15-responsive-css-frameworks-worth-considering/
It's possible to do that yourself, using percentages for css width, media queries and js fallbacks (as media queries aren't fully supported).
But those grid systems will save you times and headaches as they are for the most well tested.
To help your decision, you should consider :
- The browser support you need and those provided by the grid system.
- The size (they are lightweight for most, but some are not only grid
systems, ie Twitter bootstrap).
- Naming conventions, your are gonna
use weird css class (for exemple
span4
), chose the one you prefer,
some of them are more semantic than others, it's up to you.
- And at
least, the open sources factors : community, support, updates
frequencies...
Also, this site is a most for responsive inspirations : http://mediaqueri.es/