I found the following photo via Stumbleupon and I was really really impressed with the work done by the author for creating this picture of social networks and various Web 2.0 technologies used in the world.
This is really impressive piece of art. Full credit to Brian Solis & JESS3 for their work and I take my hats off for them.
Copyright: Brian Solis & JESS3
I am sharing the above picture under the Creative Commons License and if you want to copy this, please do so under the same.
There is another work of art done by AJ Batac on http://eggnyte.com/ and that is also very good. However, I like the one mentioned above because it segregates the portals based on their usage / category and its easy to map to your needs.
Again, the above URL is copyright of AJ Batac and is shared under Creative Commons License and I am sharing the same under the license. This is also a very good work by the author and must be acknowledged.
Also, if you want to search your favourite site within the world of web 2.0, you can do so by visiting the site http://www.go2web20.net/. This is a search engine for finding out and discovering the sites based on their tags. So off you go and find out your on useful sites of web 2.0
Please respect the copyright and enjoy the world of Web 2.0