Three that I know about are
Amaya,
NVU, and
Aptana.
I've only tried the first two, and I wasn't thrilled with either of them. They both seemed to have problems loading my external style sheet.
Apatana I just heard about, but I haven't had the opportunity to try yet.
I think that there is at least one more HTML editor for Linux, but I can't remember the name right off hand.