Here are a few checklists I have collected.

SEO Checklist

Web Site Review Checklist

Color in Web Design

Essential Pre-Launch Checklist

25 Point Web site Usability Checklist

Other Resources

Read the Checklist Manifesto (if you have not already).

Excellent online checklist: Web Developer Checklist

Downloadable checklist: SEO Checklist for Web Designers from NetTuts

Newsletter I read