Arshad Cini brings together thin fonts which are really popular among designers.These fonts are all free both for personal and commercial use:
20 Free and Popular Thin Fonts (Commercial Use Allowed)
Tag: free fonts
The 10 Best Script and Handwritten Google Web Fonts
Wonderful list of free fonts compiled by Joshua Johnson, complete with HTML and CSS code for easy implementation.
The 10 Best Script and Handwritten Google Web Fonts
Font Collection: 10 Free Retro Script Fonts
Nice collection of retro script fonts suitable for headers or small chunks of text: