I just showed up last November looking for some e-tools news and 800 post later my wife wants to break my computer. Once you get hooked your hooked hard. Just lurking around and looking in the window is pretty addictive itself, just get them to look around.
Maybe try to work on the one who seems most likely to become involved here. When he/she sees how cool this place is, they can work on the rest of your friends. It's no longer just you encouraging them to stop by, but a new "convert".