Pimp.my.Gmail series!
If you prefer a script, check out : http://userscripts.org/scripts/show/75047

This style will Pimp up the Inbox section of Gmail. There are a lot of tweaks which are included in this style, all related to the Inbox section.
Features:
+ Proper padding for inbox columns.
+ Widens mail by removing the ads & moves the 'new window', 'print' buttons above the mail. [taken from GMail - Remove ads and relocate action links (alt) style by "lOtR@userstyles", so credits to him]
+ Inbox refresh, Attach & Event invitation icons. [taken from Gmail: tango! icon theme style by "smaug@userstyles", so credits to him]
+ Multiple Inbox Lab feature : Adds a nice little icon for inbox labeled as Hotmail & Yahoo [case sensitive].

*IMPORTANT FOR MULTIPLE INBOX LAB FEATURE*
This part will not work on it's own. I've written a greasemonkey script [http://userscripts.org/scripts/show/71932] which has to be used in order to get it working.
Please do read the info at the about page there, to