1. You can click on profile pictures to rotate through them. Nice find by +MG Siegler on that one.
2. In the stream, you can click ‘j’ to navigate down to the next item or ‘k’ to navigate up. I think it’s the same keys that Gmail uses, which is probably in turn because +Paul Buchheit uses vi and created Gmail.
3. If you’re sharing a post with a small circle of people, you can prevent resharing. Click the arrow at the top-right of the post and choose “Disable reshare.”
4. If you’re looking for more fun things in your stream, the “Incoming” stream is stuff from people who are sharing with you, but who you haven’t added to a circle.
5. One great one from +Frederic Lardinois is that “there is some basic text formatting, too: (*)bold(*), (_)italics(_) and (-)strike-through(-) are the ones I’ve noticed so far.”