My go-to search engine for loading CDN libraries is CDNJS. I’ve found almost everything on a CDN by searching this site, everything from the usual Twitter Bootstrap CSS to a tiny JQuery application I’ve found on GitHub.
You can visit cdnjs.com here.
You can see the advantages and disadvantages by reading this StackOverflow thread. While it is a few years old, the advantages still outweigh the disadvantages.
If you have any web tools you’d like to share, please contact me.