Here's what I mean. In developing my ASP.NET MVC based site, I've managed to offload a great deal of the static file hosting and even some of the "work". Like so:
jQuery for my javascript framework. Instead of hosting it on my site, I use the Google CDN
Google maps, obviously "offloaded" - no real work being performed on my server - Google hosted
jQueryUI framework - Google CDN
jQueryUI CSS framework - Google CDN
jQueryUI CSS framework themes - Google CDN
So what I'm asking is this, other than what I've got listed...
What aspects of your sites have you been able to offload, or embed, from outside services?
Couple others that come to mind...
OpenAuth - take much of the authentication process work off your site Google Wave - when it comes out, take communication work off of your site