Macromedia
Boy do they have a lot to answer for. The company I work for uses it, and believe me, it makes a right mess of the code. Not to say other HTML editors don't, but when I'm trying hand edit some code (so it, you know, works in non-IE browsers) and I see this:
<td>
<div align=left><strong></strong></div>
<div align=right>
...
I really start to get annoyed.