Using em units in CSS layout allows for page components to scale in unison with a user's font-size preferences. But developing in ems within dynamically updating web apps can be very tricky. Earlier we released a script to quickly convert pixel values to ems (and vice versa) to support page scalability throughout a web site or application. We've rewritten the plugin to better follow jQuery syntax and reduce code weight, and are now releasing an updated version for download.
Update: jQuery Plugin for Retaining Scalable Interfaces with Pixel-to-Em Conversion