Check it out here;
http://webapps.uni-koeln.de/tamil/ [1]
Also has a link through to a digitised Monier Williams.
Links:
[1] http://webapps.uni-koeln.de/tamil/
[2] http://www.ays.org.uk/chanting-mohan-s-and-krishnamacharya
[3] http://www.ays.org.uk/ays-constitution