Many of you may have heard of translipi, the Javascript library to allow a webpage viewer to view Sanskrit content in the script of their choice. e.g. Check out
http://sahityam.net/wiki/Main_Page or
http://stotrasamhita.net/wiki/Main_Page, for instance: you can pick the Sanskrit script of your choice from the translipi widget on the left-bar.
I've gone ahead and implemented Grantha support in my fork of translipi:
I'm working with the translipi author on merging these changes back into the main line, but until then, if you'd like to use it, simply follow instructions on the above page, using the forked translipi.xml and translipi.js as appropriate.