all these referrals are, for some reason, windows-centric.
linux: nedit. you'll need either motif or lesstif libs for it. vim is an old standby. the zend ide runs on unix but requires the latest and greatest java vm.
mac. bbedit from barebones is probably the smoothest text editor in the world.
mac os x: pepper has a free version with a nag screen on save. very full featured.