I'd like to have a column in the messages view tree, where if I click on that column's trash icon, the message goes directly to the trash. Do not pass go, do not show me the message in the lower pane, do not collect $200. This would be really useful with getting rid of stuff: instead of click-to-preview-then-delete, it's just click-and-gone. Good first bug for an aspiring XUL developer?
I'm not sure that it is necessary to put this in core straight away. I could see many cases where people accidentally click (or just not find the column if its hidden by default). It would be something great to try as an extension, and there's documentation here on how to do just that: https://developer.mozilla.org/en/Extensions/Thunderbird/Creating_a_Custom_Column