There is a new (relatively) caching plugin in town for WordPress called WP Super Cache and after using it now for a few version, I have to say I would recommend this over the old standard WP-Cache plugin. The plugin is easy to install, easy to configure, and will produce a noticeable load time decrease for your WordPress sites. There are also options to set if you want to “digg-proof” your site, use compression, or “lock down” your site during an expected traffic spike.
