Google calls wave a marriage of e-mail and instant messaging. But to me it looks more like the kind of social network that I'd really enjoy, one where I can specify the people with whom I want to share a comment, a photo, or a video.

One problem with Facebook is that most things you share go to everybody you've friended, from relatives to your boss. But few people want to share everything-like embarrassing pictures-with everyone they know.

Judging from the description and early screenshots of the service, Wave could be perfect for sharing content with only the people you choose.

The service's basic element is called a "wave," which can be a simple text message, a collection of photos, a video, or other content. Just as with e-mail, you can choose exactly who you want to share a wave with. Those contacts can then make comments or ask questions that the whole group sees. You can view the new comments in real time; or, if you haven't been paying attention for a while, you can hit rewind and see chronologically how the wave developed. Each wave is like a new Facebook page created on the fly to share specific content with specific people.