Nvu, the free, and open source web authoring program, based on Mozilla Composer, is a program I haven't tried since its first test release - 0.17 I believe.
Back then it was pretty ropey, but in need of a web authoring program that was free, preferably open source, and could perfectly validate my HTML, I happened across the fact this had reached 1.0 and decided to give it a go.
At only 6.6Mb, it downloaded in a snap, installed in an instant, and from first impression looks beautiful. Easy to use, and yet feature-packed, with a super clean interface. As for validation, it's the nicest I've seen.