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.
   

Webmaster links

Here some important links for anyone who manages site content and positioning.

• Very usable and nice webmaster tool by yahoo.
• Microsoft's counter part, seems kind of old but there is new beta on the way.
• The almighty google webmaster tool which provides basic manage task and some useful data andstats about the site.

Plus the google analytics offers reports and nice stats, most of the webhosting companies offers this in their plans, but still google provides some benefits such as "benchmarking".

Two important tasks is to provide a sitemap and to define the robots file:

1. From sitemaps.org:

   Sitemaps are an easy way for webmasters to inform search engines about pages on their sites that are available for crawling

   Sitemaps have wide adoption since google, microsoft and yahoo are using it as defined in sitemap protocol.
2. Robots file: it is used to exclude some files from crawling. this is called The Robots Exclusion Protocol.

Hope this is useful for you.