Rui CarmoHydra has been updated to version 1.1, adding support for a hydra:// URL scheme (plus other niceties), and NetNewsWire has a new beta.
The UNIX way - on Windows
People who shy away from Cygwin due to its open, free development model might want to try out Windows Services for Unix (formerly called Interix). Interest on it surfaces once in a while - here's a short review.
Qt for Mac OS X
Although I've always liked the clean internals of Qt, I've shied away from KDE due to the utterly tasteless (and sometimes fiddly) UI design of many of its apps (my brain is just not wired that way, I guess - I need better function beneath nice form). Apparently Trolltech has much of it now running natively under Mac OS X, even to the point of getting KOffice and Konqueror to look like this:
It won't actually improve the applications themselves, but at least there's another way to run them on Mac OS X besides X11.