First, a rich text-to HTML converter. You can use it alongside WordPad to get a ghetto Dreamweaver.
I was looking for a quick way to convert some RTF documents to HTML. Parsing the RTF was too much effort. Pasting into Dreamweaver seemed to strip formatting. I then thought of an idea that would make this very easy.
You can paste rich text into a "ContentEditable" element in Internet Explorer, and it will retain much of its formatting - and then getting the innerHTML of that element produces the HTML!
Bold/italic/underline, fonts, colors, indentation, and even tables(!) are supported. I threw together a demo here. (Requires Internet Explorer). Also of note is this cross-browser rich text editor that also works in Mozilla using designMode.
Next, a small tool for finding colors. You know the eyedropper tool in Photoshop that can pick up a color from an image? This will do something similar for anything visible on your screen. It will grab the RGB value of the color just underneath your cursor, in any Windows program.
Download it here (zip, no installer). Run the program and press the space bar to update the color to be whatever color is beneath the mouse. The idea came from altAnswerColor from Altuit.
Finally, I use Microsoft Paint occasionally to draw simple lines and diagrams. To get arrows, I'll have to copy screenshots from Word or something. I wrote this small program to have quicker access to arrows.
When you click an arrow, it places an image on the clipboard that can be quickly pasted into Paint. Simple, yet useful.