Downloadermac is a Cocoa application for downloading items from the Internet. It frees up your browser for other tasks by reducing the load on your Web browser's process by creating a thread just for downloading items.(e.g. firefox-bin, safari). It is tested on both Panther (10.3.9) and Leopard (10.5).
Movgrab is a command-line movie downloader for sites like YouTube. It has no dependencies; everything that's needed should be there in the tar.gz package. Movgrab can connect through an HTTP proxy, can output the download to stdout for piping into another program, and can fork into the background to free up the console. When forked into the background, its progress can still be seen in a ps list.
MuDownManager is a program for managing downloads from Megaupload and Rapidshare for premium members. It is lightweight and cross-platform. Downloads can be started in a batch by specifying a list of URLs. Links can be copied directly from your preferred Web browser and pasted into MuDownManager. MuDownManager lets you skip LinkBucks. It has a very simple and intuitive GUI. It is pluggable, allowing support for other download sites to be added in the future.