Ask The Builder
Syndicated columnist Tim Carter promises to answer 50 questions a day here.

DoItYourself.com
The repair encyclopedia is short on style, but long on information.

The Home Maintenence and Repair Database
Few bells, fewer whistles, great info: The strong-but-silent type.

This Old House
The genetically handy will be drawn by instinct to this site, where even raising a barn (with indoor plumbing, central heat and skylights) looks easy.

The WWW Bike Repair Guide
So that's how you build a wheel!