Google Books

I found this product interesting, but only in a purely theoretical sense. I do not find the prospect of reading a text off a screen appealing, but I suppose I would suggest it as a resource for quick reference work.

Facebook

I think that facebook can be both useful and a time-waster, it completely depends on the user.

Wikipedia

I went to the entry on Virginia Woolf and added a fact, which I was surprised was missing, so I suppose I didn't find it difficult to find an entry that needed editing. I was surprised at how easy it was to edit an article.

Not to my taste

While Delicious seems useful for organizing your own favourite websites and discovering others, I don't find it very user-friendly.