Live Mesh is part of Microsoft’s new online activities. In contrast to Apple’s MobleMe it concentrates on syncing files and folders from different PCs and Macs. It currently does not include syncing of addressbook entries, calendars or mails. Anyway Live Mesh is free.
Microsoft offers 5GB harddisk space that can be accessed using their Live Mesh client software (available for Windows and Mac) or thru their website.