Cacher is the code snippet organizer for pro developers

http://bootswatch.com/

http://startbootstrap.com/template-categories/all/

http://www.webdesignerdepot.com/2013/07/how-to-modify-bootstrap-simply-and-effectively/

Good list of tools, like templates and themes, custom build tools, add-ons, and snippets. 

Font Awesome
http://bootsnipp.com - themes, templates, form and button builders, snippets, etc.

http://www.bootply.com/
IDE and Snippets

Less Like Bootstrap – 5 Ways To Customize Your Designs
http://blog.jetstrap.com/2013/07/less-like-bootstrap/