Yup, you guys got what I was talking about. Trillian is a program I use for it's invisibility as well. Also winamp although I'm trying to abandon it....
Nice try on TrayIt, but that's for minimized applications only. Also, the first time I used it everything I had open suddenly closed. So, take that for what you will. HideIt was actually the program I remembered (and even used once upon a time) but that's for background utils you don't want to see at all. Any other suggestions? Google wasn't helpful, neither was sourceforge. Feature request?