+I have always thought Windows fonts cannot be used for display. Could you describe how you use Character Palette to do that?+
Well, not "display" in the sense of opening a file using an OpenType font on the Mac and seeing it display properly. What I do in Character Palette with an OpenType font like Sanskrit2003 is scroll through the font to find the elements I want and double-click them to enter them in a document. Of course this workaround is feasible only for the occasional word, not for whole sentences or paragraphs. I'm not a big time user of any of this, so I can manage for the occasional word I want.
+The reason they do this is because a lot of documents and web pages could specify Arial in them and users would get the idea that OS X does not support Devanagari, Tamil, Tibetan, etc unless they switch the font, which is impossible in Safari.+
Yeah, I can see the reason; but wouldn't it be easier in the long run to just enable OpenType fonts so everyone can use the same fonts? And it is annoying that you can't specify fonts in Safari like in Camino.
+I agree, but have doubts this will happen soon. Perhaps more likely is an app like Mellel which does OpenType could be expanded to cover these scripts.+
Several years ago the developer of Mellel assured me that v.2 would support Indic scripts. But it never happened.
+In the meantime, OpenOffice/X11 does work for display I think.+
Yes, OpenType fonts can be used in OpenOffice/X11 (which is no longer being developed, BTW, now that there's a native OS X version). But not AAT fonts.
+This might interest you:+
http://discussions.apple.com/thread.jspa?threadID=1577715&tstart=0
Indeed, though much of it is over my head. I just want to be able to use the same fonts for Indic languages as everyone else, just as I can in Chinese, etc.