While I was working on the video lessons for BlogClassroom, I came across a WordPress plugin called OneClick, developed by Anirudh Sanjeev.
The OneClick installer is perfect if you want to save time downloading and extracting zipped plugin or theme files then uploading them to your WordPress blog via FTP.
After you've installed and activated OneClick, you'll be able to automatically install plugins from either their zip file on your hard drive or directly from the zipped file's URL.
In WordPress 2.5.1, you access OneClick from the Dashboard. After installing a plugin, all that's left for you to do is activate it.
OneClick has a plethora of features, all outlined in the WordPress Plugin Directory information for OneClick. That page also includes a download link for the plugin.
The only problem I experienced with the plugin was not being able to delete one of the plugins (via either FTP or cPanel) that I'd installed with OneClick.
Turns out that had I bothered to read the instructions, I wouldn't have had to bug Steve, as there's a fix for that too. It's called the purgatory module, and is included with the plugin.
The OneClick installer might be the LAST plugin that you ever download, extract and then upload to your wp-content folder, and that's a GOOD thing.