Web Tools I actually use: flickr

Flickr - (http://www.flickr.com )

Flickr lets you share pictures. You upload your pictures to flickr, and other people can see them.

You can tag them with words or phrases that will make it easier for (and others) to find your pictures.

People can comment on your pictures. You and others can "annotate" your pictures so you can identify people in a group shot, for instance.

And since you can take digital pictures of things, you could take a photo of a whiteboard after a brainstorming session and upload it to flickr, and people could comment on it.

Lots of possibilities for geography classes, you can find pictures of Transylvania or any region of the world you can imagine.

You have control over who sees your photos, you can set photos so that only you see them (so at least they would be backed up in case your hard drive ever died), so only family can see them (so all the pictures of children in your life), so only friends can see them (say pictures from a drunken party), or that friends and family can see them.