Gif Wizard can help you reduce the size of your graphics for quicker loading. The HTML 4.0 Specification is a good reference for HTML 4.0. HTML Goodies HTML Help by the Web Design Group. Kira's Web Toolbox contains many useful goodies. There are exclusive tools, including a 216 color square which, when you click a color, will return the hex value.
Lynx is the text-based browser in most common use.
Spyglass no longer supports this validator, but it's still available and it still works. The Web Developer's Virtual Library Still Yet Another HTML-info source. You may wish to consider how your page can be accessed by the visually impaired. The RNIB's Guide to Accessible Web page design.