Myself and our designers use to design by the 960 grid, or create our own grid, to a greater width of 992px (to fit a res of 1024 x 768).
The web has progressed so much that our team now break outside these restrictive grids and are using technologies that expand and shrink to fill small to large resolutions. Our designers work closely with our talented developers and programmers to create advanced interfaces where possible.
That said, we still always set up our designs with a grid. I use Photoshop's grid and set its grid prefs to something like;
- Gridline Every 24px with 3 Subdivisions ... or ..
- Gridline Every 28px with 4 Subdivisions.
Then, using Photoshop's shapes, I setup a grid of columns (like the downloadable asset at 960 Grid), where each column is a division of the grid in my Photoshop prefs I've set. This column grid sits on the top layer in my file and I lock it, set it to transparent and toggle hide and reveal as I design, to use as a guide for columns. I never start a major content block/element inside a column - instead, every element aligns with a column.
I also work to a baseline grid theory, meaning each line of text whether heading, paragraph, bullet, button text etc are all using leading that relates back to my grid system and all text lies on the baseline grid. For example, if my Photoshop grid is set to Gridline Every 24px with 3 Subdivisions, then my leading is a division of 8px or even 24px... 24, 48, 96 etc - increasing as my text styles increase for headings etc.
This makes for strong design! Hope this helps.