If you use Gmail and have a keyboard with a numeric keypad, try turning on the Labs feature, and then turn on the “Custom keyboard shortcuts” gadget.

This will create a new tab under settings for your keyboard shortcuts. Following is a proposed set of shortcuts allowing for faster browsing and sorting, with what I consider a logical organization. Note that I’m not showing shortcuts for every command, only the ones I propose changing.

Action Key(s)
Back to threadlist 4
Newer conversation 8
Older conversation 2
Select conversation 5
Star conversation +
Report as spam *
Move to trash
Open conversation 6
Previous message 9
Next message 3