Blue UI Kit
Grab the free PSD here: http://www.icondeposit.com/design:130
This Blue UI kit includes everything from checkboxes, radio buttons, and toolbars, to search boxes and tooltips. Everything is entirely vector and can be scaled to any size if needed. To get a retina version of this just double the size and scale the styles (when re-sizing). It includes a Photoshop PSD like always, enjoy :)