You can use your PIV-enabled YubiKey on a variety of platforms.
Windows has built-in PIV support. You can use it for logging in to an Active Directory connected machine, to encrypt files using BitLocker, to sign executables using signtool.exe, etc. For more information, see: https://technet.microsoft.com/en-us/library/ee706526(v=ws.10).aspx
Linux and OS X support PIV by using the tools provided by the OpenSC project.
This enables you to sign software, to authenticate over SSH, and so on.