12/7/11
You can use QuickTime Player in Lion to capture a single frame of video and save it to an image file. By using the Edit, Copy command you can grab the current frame, and then paste it into Photoshop or Preview. You can also use this technique to quickly grab a still image when using iMovie.
12/5/11
If you have an Airport Extreme or a Time Capsule you can create a separate guest network. This appears as a different wi-fi network than your main one. Users of the guest network cannot see the computers or other devices on the main network. Setting one up in advance is a good idea so you can grant visitors access to your Internet connection without worry.
