I would like to have support for sending URLs for it to download via the command-line (where it will show the main window and download the specified url, then close the main window when done downloading and have it stay running in the system tray) and support for Rapidshare, etc. added to it.

Here's the description of it from its site:

ConnectFusion Download Accelerator is a very fast open source download manager. It will accelerate your downloads from the Internet and resume broken connections. It includes an easy-to-use interface and its installation does not interfere with the normal behavior of your browser. ConnectFusion Download Accelerator is 100% free, never expires, and does not contain any spyware or advertisement. Its source is freely available to any one who wants to inspect or modify it.

Homepage - http://www.connectfusion.com/
Screenshots - http://www.connectfusion.com/screen.htm
Source - https://github.com/Zero3K/connectfusion
Download - http://www.connectfusion.com/connectfusion.exe
Size - 1.17 MB