Try CWComm, http://www.mrx.com.au/d_cwcom.htm
. You can practice offline or send to others online. You can use the down-arrow key on the keyboard like a straight key. I found this very hard to do effectively. You can use the buttons on your mouse like a paddle. I found the mouse much easier to use than the down-arrow key. You can wire a paddle or key to your serial port. This method is obviously the most realistic.