I have been coming across several useful links that can aid Usability and UX/UI efforts. I have been getting there through various sources such as Linked in, Book readings and of course fellow class mates as well.
I came across this article in my LinkedIn news today. Its showcases Top 20 free UI kits for web designers. You can download them for free and most of them are done in HTML and CSS3
Another free tool is 365 PSD where you can download cool designs as photoshop source files.
The following resources are from the book Web Design for ROI