I found this interesting from Stephen Walther:10 Essential Tools for building ASP.NET Websites

Now whenever starting a new website, i will prefer to this article.

Short summary:

1. Sprite and Image Optimization Framework

2. Microsoft Ajax Minifier

3. ySlow

4. ELMAH

5. Pingdom

6. Host Tracker

7. HTML Spell Checker

8. IIS SEO Toolkit

9. LinqPad

10. .NET Reflector