Yahoo Mail and the little checkbox that could
The checkbox's triumphant return is testament to the mistakes designers often make when they cater to their power users. It also shows the need for applications to focus on simple, visual, and adaptive (as in "single click") controls. Before they added back in the CheckBox you could still select multiple messages by holding the Ctrl key or select all messages by pressing Ctrl-A, but these shortcuts were difficult to communicate to anyone but the power desktop user. The checkbox, however, is easy to understand.
The other cool thing about the checkbox (and a reason why it could be a cool addition even to desktop mail clients) is that it lets you interact with multiple messages or select all messages using only your mouse. Trying to explain to your Grandmother that she needs to hold a key on her keyboard while carefully clicking on each message is neigh on impossible, it is easier for her to just move one message at a time. But give her a checkbox and she's in business! The checkbox makes organizing into folders much more accessible to all users, power or otherwise.
This brings us to the other old-is-new feature recently added back to Yahoo Mail: the move button. Again, you can move messages just by dragging and dropping, but that requires a precise (i.e. difficult) series of mouse moves that make the application less than accessible. By adding back the checkbox and the move button Yahoo Mail now has the power of a Web 2.0 mail client but the flexibility to be used just like a good old fashion "Hotmail inspired" mail client. Which just goes to show that the newest, flashiest, and most amazing features are nothing but liabilities if only 10% of your audience are comfortable using them.
Interested in doing more with Yahoo Mail? Check out our top 11 list of tips and tricks.