If you frequently download from Rapidshare, then a multi-threaded downloader like Progressive Downloader ensures reliable, fast downloading.
Progressive Downloader is free with support for HTTP(S), FTP, SFTP (SSH) and MMS protocols. One of the most useful features is that you can control how many threads are used to download a file enabling you to control how much bandwidth downloads take-up. Progressive Downloader also features a built-in mirror search which means it tries to find mirrors for large files.
Along with the multi-thread downloading features, you should experience super fast downloads as every thread can use its own server. In addition, Progressive Downloader also supports AppleScript and Automator which means you can automate specific actions and functions for use with a wide range of Mac apps. The websites supported by Progressive Downloader include Megaupload, Rapidshare and Filefactory.
The interface is very slick with mutli-colored LEDs to indicate the status of a download. To access and view thread details just CMD-click on a download and you can deactivate or change instantly.
Progressive Downloader tends to be a bit heavy on resources and may hog your CPU when you're downloading a lot of files. However, it does download files very quickly and you should notice a significant speed increase compared to downloading without it.
Progressive Downloader is a powerful download manager that should speed-up your downloads from file hosting sites and more.