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.
phoneutria is a Web crawler that is multi-threaded, scalable, high performance, extensible, and polite. It can be used to crawl, index, load-test, or even download any Web or enterprise domain and is configurable through a XML configuration file. Phoneutria can be used for either checking the links of a Web site or for load-testing purposes (i.e. the level of politeness can be configured). It provides a plug-in mechanism for further extensions.