This may be a bit of a stretch, but something I think is severely lacking on Macs is a *good* software update utility for non-App Store software. Mac Update is decent but absurdly expensive. It'd be wonderful to have the Parallels Toolbox have such a feature to scan for and automatically update software in a way that's on-par with PSI for Windows.
It would be great to have the feature for the update installed applications, especially from external developers like doxygen, etc.