So far, the one Windows app that I miss is Live Writer. There’s at least one Mac one that I like better than any Windows’ counterpart – iPhoto. I tried Aperture, but don’t really need those advanced features.
All that said, I’m discovering that all this Windows vs. Mac stuff comes down to some people being really strange. With Windows 7, both operating systems are more alike than they are different, and each does certain things well. I appreciate the hardware more than the OS on the Mac side, actually (although that comes at a price).