Palasthotel

greatestview

This plugin redirects attachment pages to the post, where they are placed (via 301). If there is no parent page, it redirects back to the WordPress home URL (via 302).
Further, when editing a post, the option to link images to their attachment page is hidden via CSS (except it is selected by default).

Disable Attachment Pages

Redirects attachment pages to the post, where they are placed, and hides backend option to link images to attachment page (if not default).

Fabian

Traffic Limiter is a useful addon for blogs with many media files which can cause high data traffic. 
There are three traffic limits to avoid over traffic costs: daily, weekly and monthly limit. If one of these limits is exceeded downloads will either be redirected to a custom URL or a custom message is displayed. For images you can define a fallback icon which is displayed instead of the message. Additionally a download bandwidth can be set for registered users and guests.
Also included is a statistic system which displays the current traffic consumption and individual file stats to see which media produces the most traffic.
All files are sent to the browser by a PHP script, supporting the most HTTP headers like <code>If-Modified-Since</code> (for caching) and <code>Range</code> (for partial downloads)
If the Apache extension <code>mod_rewrite</code> is installed download links stay the same, if not links to media files are automatically redirected. It is recommended to install <code>mod_rewrite</code>, although this plugin works without this extension.
Note: If you provide lots of downloads or media files you should try my download manager <a href="https://wordpress.org/extend/plugins/wp-filebase/" title="WP-Filebase" rel="ugc">WP-Filebase</a>.

Traffic Limiter

Limits traffic and download bandwidth of media files. Additionally this plugin includes a download statistic system.

Disable Attachment Pages vs Traffic Limiter