Diigo.

Diigo can be used for everyone, but businesses really get a kick out of it.
Businesses can use Diigo to communicate in a new, easy way. It's an easy way to share comments and links with coworkers and even costumers.Online bookmarking is a stepping stone for greatness.

High school students and college students can also have a good use for Diigo. Diigo can help them share information and link information to other people. It's also easier to organize information. Since high school students usually have a problem with organization, this can be a very helpful tool. It is also helpful because it can be reached anywhere. You can even read bookmarks without being online.
Something I find really interesting is that you can capture a picture of the screen and annotate the screen shot. You can add sticky notes with your own comments. This way, you can share your own information that you need someone to see. You can also highlight things to add emphasis on something important. You can even highlight in different colors! Privacy controls can always control safety and privacy for high school students.

Diigo can really be a helpful tool for everyone. Overall, Diigo is a very useful tool.