I found this nice little app today, a gem for any 8bit-junkies out there 
As far as I can see, the author must be a great guy, although Swedish 
http://www.imitationpickles.org/ludum/2007/12/13/sfxr-sound-effects-for-all/
Windows only. :evil:
And Linux
Any chance you can use Vmware / Parallels?
Yes, but I’m not going to pay for virtualization software and a copy of Windows. There are plenty of free alternatives, however…
That’s a well-known one. It’s nowhere near as sophisticated or convenient as the one you showed, though. I just use the stuff that is built into Logic Pro for the most part, but that requires significantly more work and know-how.
Then you have bootcamp and Linux as free alternatives Although booting up in Linux to make some blippy sounds isnt necessarily what you want either. Personally I am aiming for a solution with Fusion.
Boot Camp is free. A copy of Windows is not. Linux would be the best bet, but I’m not willing to devote any portion of my hard disk to it yet, as I need the space for other things. I tried running Linux off of a CD, but it didn’t give me very good performance.
there is an OSX version. I will dig out the link when I get home. If not you can hunt it down via google.
edit: 
http://www.timdoug.com/sfxr-sdl-macosx-intel-10.5-alpha.zip
http://www.absoluteterritory.org/software/sfxr-mac-ppc.zip
Cheers.
Only for PPC machines or ones that have Leopard. I have neither. 
so you are running intel with tiger?
well you could always run the ppc version under rosetta or re-compile it yourself:
http://www.absoluteterritory.org/software/sfxr.tar.bz2
Cheers.
It does not run in Rosetta, and I don’t know how to compile anything. Instructions for this?
(Don’t waste your time unless it’s easy to get the info over here, of course.)
Sorry didn’t see this… posted a version here that works fine on Leopard Intel…
There is a browser version as well that allows you to download the samples you create
http://www.superflashbros.net/as3sfxr/