Great plugin so far. But with out having a with_front option, sites that are running Multisite in directories will find themselves with a prefix of /blog/go/. Have you though about this?
Also, what about an options page to control the prefix (rewrite) instead of using go, maybe I might want to use refer or suggests.
;)
http://wordpress.org/extend/plugins/simple-urls/
Doing some follow up because I just came across this plugin when I needed to modify the prefix. Would love a filter or a definition I could redefine.
Had to unregister and reregister the CPT to do it my way.
It's as simple as:
'rewrite' => array( 'slug' => apply_filters( 'simple_url_slug', 'go' ), 'with_front' => false )