Tips & Samples:
Authoring Features
Control Pad Tutorial
Style Sheets Guide
Showcase Pages I
Showcase Pages II
Multimedia Gallery
ActiveX Gallery

References:
HTML Reference
SGML DTD for IE 2.0
ActiveX Controls
Controls FAQ
IE Logo Program
W3C CSS Spec
W3C HTML3/CSS
W3C Layout Spec
W3C Object Spec

Authoring tools:
Publishing Tools Guide
ActiveX Control Pad
HTML Layout Control
IA Overview
IA for Word
IA for Excel
IA for PowerPoint
IA for Access
IA for Schedule+
Microsoft FrontPage
Animation Player

Browsers/viewers:
IE 2.0 Features
IE 3.0 Beta
Word Viewer
Excel Viewer
PowerPoint Viewer
VRML Add-In
HTML Wizard