There are several caching plugins available for WordPress sites which can help to improve your website loading time and overall performance. They can also help your site to handle large spikes in traffic like the Slashdot effect. Below are some that work the best on DreamHost's servers:
This plugin creates a static file cache of your site and loads that instead of using PHP to generate the page. Picking up where WP-Cache left off, this plugin has included advanced features as well as a plugin and hooks system. It is included with all new deluxe One-Click Installs of WordPress done by DreamHost. If you're on shared hosting, this is the best option. An installation guide can be found here: Installing WP Super Cache
This is probably one of the most user-friendly caching plugins out there and is an outstanding alternative for most end users.
This plugin is also excellent, and gaining a lot of traction in the community, in part due to its inclusion of CDN features.
Page Speed Optimization
Google Pagespeed is actually a cache. What it does is minify your files (make them smaller) and serves up those files instead of making WordPress process them. You can use 'Page Speed Optimization' as needed. View the following article for further details:
VPS servers only
Normal VPS users have XCache available in the DreamHost panel which ties in with W3TC. If instead you want to self-install Memcached, try using the plugin Batcache to speed up WP.
DreamPress uses Varnish Caching on the server which is a great thing for non-logged in users. Logged-in users benefit from Memcached which is also installed with DreamPress.
Using DreamSpeed, your static content will be cached on the CDN which will ease the load on your account and can speed up your WordPress installation. Once you have signed up for DreamSpeed CDN, you can log into your WordPress dashboard and enable the plugin.