OT (slightly): what's the best X-platform icon maker that runs on a Mac?

[Graham Samuel]

I used to use Iconographer, but it hasn't been updated since 2003 -  
you can still get it (for free) but I can't think it knows about Vista  
etc. I know this has been discussed before, but what do people use  
currently? I couldn't find anything after 2007 in the archive, and  
that conversation was about Iconographer anyway!

TIA

Graham