Fresh Performance Cache ($18)
CDN Linker (Free)
I would normally recommend W3 Total Cache for this but lately I’ve not been including it since I’ve started to use Varnish caching. CDN Linker simply changes all of your media, CSS, and JS references to any URL you’d like, making it easy to setup a CDN on your domain. Don’t know what a CDN is? Well a Content Distribution Network is a series of servers that allows content to load faster on your site. I highly recommend MaxCDN if you’re interested in using a CDN on your site (This can get pricey but on bigger sites it’s a must).
Anything I missed on my list? Let me know what you use on your site in the comments!