Elastic Columns is a lightweight jQuery plugin that will suit your needs if you want to build a grid of items using columns with equal widths.
matchHeight is a more robust, responsive equal heights plugin for jQuery. It makes the height of all selected elements exactly equal.
equalize.js is a jQuery plugin for equalizing the height or width of your elements. Equalize will accept any of the jQuery Dimension methods: height, outerHeight, innerHeight, width, outerWidth, innerWidth.