Masonry is a dynamic grid layout plugin for jQuery. Think of it as the flip-side of CSS floats. Whereas floating arranges elements horizontally then vertically, Masonry arranges elements vertically, positioning each element in the next open spot in the grid.
The result minimizes vertical gaps between elements of varying height, just like a mason fitting stones in a wall.
Gridster is a jQuery plugin that allows building intuitive draggable layouts from elements spanning multiple columns. You can even dynamically add and remove elements from the grid. It is on par with sliced bread, or possibly better.
Wookmark plugin lays out a series of elements in a dynamic column grid. It detects the size of the window and automatically organizes the boxes into columns. Resize your browser to see the layout adjust.