For years one of the tools I used a lot was Microsofts Live Mesh tool. This tool made syncing files across multiple computers absolute childs play. You just set up the folders on all the required machines and the software just kept everything in sync.
However a year or so ago, Microsoft decided in their infinite wisdom to replace it with SkyDrive. The problem is that although SkyDrive does a great job to a degree it has 2 major issues as far as I'm concerned. 1) The folders must all be located under one parent folder and 2) there is total storage size limit and an individual file size limit of 2GB. This was particularly an issue when wanting to sync ISO images or large movies.