Rewrititsu: The Gentlemanly Art of .htaccess Rewrites Pt. 2

Last week I posted some simple htaccess rewrites. This week I want to take it a step further and look at the RewriteCond property, along with three neat rewrites you can use.
As its name suggests, RewriteCond allows you to set conditions for a rewrite, including filtering by referer, saved information (in cookies), server information, and more. Each condition is applied to each rewrite rule, from the conditions line downwards, until it hits a rule marked as the "last rule" with an [L] tag. (For more tags see: Regex Character Definitions for htaccess) Following rules will be executed as well, but not with the condition applied.
The available conditions are:






