/// Web-aps:

• Favicon Creator
• Flash Colour Scheme Generator
• Lightbox Javascript Usage (what everyone always asks about)
• Lorem Ipsum Creator (to fill out the blanks)
• Online PDF Convertor
• Thumbalizr (create screenshots of websites in an instant)
• Browsershotz.org (create screenshots of your website with different browsers)

/// Tools:

• Yahoo currentcy convertor
• Keyword Checker
• Multi DNS Checker
• XML Sitemap Creator (usefull to submit to Google)
• Waybackmachine (to view the history of your domain)

/// Usefull sites:

• Corz .htaccess guide
• Official Ad Standards 
• Urban Dictionary
• Versiontracker MacOS (downloads, utilities & tools)
• Webmaster tools (Lots of stuff to backtrack links, check pageranks …)
• Wordpress permalinks: A nice little guide

/// Video sites:

• Vimeo (like YouTube only smaller and more community like)