NSIS for the Mac?

I know there is no 'NSIS for Mac' (any plans for such?), but I have a Java app for which I need to build an installer for Mac OS X. This is for a cross-platform app for which I'm using NSIS for the Windows version and need a good similar utility for the Mac version. (And, actually, for Unix/Linux while I'm asking.) Anybody have something they would recommend?

Thanks...

You could try IzPack. It is a pure java installer and so it is complete platform independant.
I used it for some projects and the people working on it are very kind and helpful.

grassu