You can add JavaScript and CSS files to your master page if you want to overwrite some default styles or add some functionality via a new script.
Here's how you can add custom styles to a specific site collection in SharePoint 2010.
The recently modified panel is annoying. Here's how you hide it.
Eliminate the need to duplicate files across site collections.
Here's a cool trick to run JavaScript on SharePoint 2010 wiki pages without editing the master page.
A useful tool for building CAML queries in Microsoft SharePoint 2010.
Elements added to a SharePoint 2010 master page may show up in every dialog box. Learn how to remove them from dialog boxes.