Eyes-free: Move trackball or D-Pad to get voice indication, and press trackball or D-Pad to select. Try to listen to a SMS and reply it with your eyes closed!
Delete a channel: Long press it in the Manage Channel page.
Gmail: To only listen to new emails, you will need to go to your Gmail Settings in your desktop web broswer, go to Forwarding and POP/IMAP, choose: Enable POP for mail that arrives from now on. Otherwise, you may experience a long download time for the first time.
Enabling POP - Gmail Help
Weather: You can modify the zip code of the weather channel to your local zip code (Menu->Manage Channels->Weather->Customize).
Stock: You can add more stock symbols to the stock channel (Menu->Manage Channels->Stock->Customize).