My choice for best web applications

1. Photsynth: It needs an active x pluggin for Internet Explorer, but it's like using something from the future now. The way the navigation goes through the 3d environment is great and the way I order photos in a 2d model is superb.
   
2. Google Maps - Live Maps: the entire map can be seen as a gigapixel image, street view is truly useful and the directions tools that both sites offer are a great way to show how web 2.0 apps are afecting nowadays rutine.
   
3. Google Reader: the best way to keep you updated, it has a high performance and forget about having to check manually every feed either in your browser or surfing page by page. In 5 minutes I can overview more than 80 feeds. Apart from the mail web systems, I thinks this is the most useful web software available for professionals.
   
4. Yahoo: the ultimate usability portal, well studied components which give the user a lot of information in one page.
   
5. Flickr: great community where people can actually know the whole world with high quality photos taken from great photographers. It has great sense of usability (yahoo trademark), and you can spend a whole afternoon using it in conjunction with the apps described at point 2.
   
6. Microsoft's Hotmail: It's fast to manage, I can do a lot of things faster than If I were using gmail or yahoo mail, it's very intuitive with the "right click" options.
   
7. iGoogle: the extensions and the widgets offered are great, you can actually set your internet "dashboard" here.
   
8. Youtube: the ultimate web 2.0 site. Huge community, huge traffic, and very entertaining site.
   

Google's Design Guidelines

I read here about the google design guidelines, the "beautiful" concept caught my attention the most: "delight the eye without distracting the mind". Other guidelines:

1. Useful: focus on people - their lives, their work, their dreams.
2. Fast: every millisecond counts.
3. Simple: simplicity is powerful.
4. Engaging: engage beginners and attract experts.
5. Innovative: dare to be innovative.
6. Universal: design for the world.
7. Profitable: plan for today's and tomorrow's business.
8. Beautiful: delight the eye without distracting the mind.
9. Trustworthy: be worthy of people's trust.
10. Personable: add a human touch.

Source: Google System.