In the new Yahoo! mail I can select multiple checkboxes against my email subjects and press k to perform the action Mark as read.
Is there a similar alternative in Gmail?
Gmail "Mark as Read": Shift + i
Display a list of Gmail keyboard shortcuts: Shift + / or (?)
Select all unread conversations: *, then u
Also, you could map K to "Mark as read," just like in Yahoo mail. The "Custom keyboard shortcuts" Gmail labs feature lets you customize your keyboard shortcut mappings. It adds a new Settings tab from which you can remap keys to various actions.
...or you can add a "Mark as Read" button via another Gmail labs feature.
Shift + I Mark as read - Marks your message as 'read' and skip to the next message.
Shift + U Mark as unread - Marks your message as 'unread' so you can go back to it later.
In Gmail you can use ?, that is Shift + / for the ?, you can see the keyboard shortcuts.
Shift+I - Mark as Read and move on to the next message.
FYI - you may have to activate Keyboard Shortcuts before they work. They seem to be inactive by default. You can find this option at the bottom of the [?] screen.