If you want to select a range of messages in Gmail to do something with, you can do so by clicking on the first checkbox in the range, then hold down the Shift key and click the last checkbox in the range. This will select all of the message between the two clicks (including the ones you clicked on). This is a pretty cool feature, and I've noticed other sites starting to do stuff like this to so that it is easy to select things in bulk with checkboxes.