Konquerer supports Tamil fonts neatly, once made at the proper scale under your font directory and served to X. Widely used Netscape, however, is a problem. Netscape uses only 75 dpi fonts for display. You might have noticed this even while viewing Roman fonts, and got annoyed seeing small fonts. That being the case with Roman, Tamil is impossible to comprehend under 75 dpi. This can, however, be fixed by specifying the appropriate resources in your .Xdefaults file:
Netscape*documentFonts.sizeIncrement: 20 Netscape*documentFonts.xResolution*iso-8859-1: 150 Netscape*documentFonts.yResolution.iso-8859-1: 150
Remember that TSCII fonts are used as ISO-8859-1 fonts. The parameter 150 is arbitrary; I have seen some fonts scaling neatly under 100 itself (TSCparanar, for one) which is good enough for viewing. If you are still not satisfied with what you see, try using anti-aliasing under X.