apt-fast is a shell script to accelerate apt-get downloads using Axel, a command line download accelerator. Based on apt-fast, some other scripts have been created and I though they are worth mentioning:

JDownloader is a a java-based tool that completely automates the downloading process. It can be very helpful for websites such as Rapidshare.com or Megaupload.com for both premium and free users.

FatRat comes with many very interesting options. For one, it can download from HTTP(S)/FTP, RapidShare free and even YouTube. But FatRat can also download torrents, (it has BitTorrent support) has RSS feed support + special functions for TV shows and podcasts, support for SOCKS5 and HTTP proxies and even remote control via Jabber and a web interface and of course, a scheduler.