This site would be very useful when doing research, especially if you aren't always on your own computer. This way you can be anywhere and look up the sites you tagged for a project or a paper.
When it comes to teaching, YES! I think this would be helpful as well. I could see this site being a great tool for teachers to share ideas and network with one another. Sharing ideas is the best part, I think, why re-invent the wheel when you could use someone else idea or spark new ideas with a website you saw.
This could be very helpful in the future!