Discovering Web 2.0 Tools

There are plenty of applications/tools to choose from (200+), so how to make up one's mind?

I'm not sure how or why, but I did end up looking at one interesting literary site, a musical one and another that is environmentally conscious. I probably ended up having a look at these because these are different aspects of my life. Notably on that point, there were no listings that are spiritual at all. Is that asking too much or is it just a reflection on where everyone's interest lies?

onesentence.org was enjoyable for the humour and succintness, telling a story in the space of, you guessed it, one sentence.
pandora.com seemed like a good music site, but was its use was restricted outside the U.S. Hence, I found mystrands.com a better option, though because of restrictions on our work computers, I couldn't listen to anything (damn!)
Lastly, begreennow.com wasn't necessarily outstanding, as there are so many of these types of sites around nowadays, but it is instructive and interactive and obviously more conscious in many ways than quite a number of the tools that were given awards.