Josh Eaton

A small plugin that lets you “hide” the front-end of a site, all front-end requests of logged-in users are redirected to the WP Dashboard (filterable).
Useful mainly for developers, if you’re developing a site and want to give users access to see the dashboard while you’re working on the front-end. Also can be used if you have a site with no front-end and always want users to stay on the dashboard.
Filters included:
<ul>
<li><code>rfe_redirect_caps</code>: Control capabilities required to bypass redirect, lets Administrators access front-end by default (default: <code>manage_options</code>) </li>
<li><code>rfe_redirect_url</code>: Change the redirect URL (default: <code>admin_url()</code>)</li>
</ul>

Redirect Front-end

A small plugin that lets you "hide" the front-end of a site, redirecting to the WP Dashboard.

moxu

I created this plugin because i wanted this feature (to set a specific locale for frontend) out of my themes. I’m assuming i’m not the only one who would preffer to have the backend en_US only, so here it is…
It’s not tested with other versions of wordpress except 3.4, but it should work without a problem at least from 3.0 onwards.
This plugin assumes you’re not using a translation plugin , so, if you have bilingual or multilimgual blogs, use with caution (and let me know … especially with qtranslate 🙂 ).
I’t not multisite tested/ready yet.

LanguageBack

Simple , minimalistic plugin that lets you set different locale for frontend and backend.

Redirect Front-end vs LanguageBack