For an excellent paper on the pre Portugese history of Goa, click on the following link to view the work of  Prof. George Moraes

Pre-Portugese history of GOA

For an interesting overview of Goa's very early history click below (courtesy of Goacom)

Goa' early history (2000 BC - 1500 AD)

To understand the Indian Liberation of Goa the following link gives an animated overview of proceedings (courtesy of Goacom)

The Liberation of GOA

BOOKS

If you are visiting Goa and are interested in its history you will find the following link helpful in choosing your books

Books List

The list has been provided by Frederick Noronha he has added the following note

Dear all: Check out this list of Goa books available with the Other
India Bookstore in Mapusa [http://www.otherindiabookstore.com]

Sorry that some edges of the catalogue have got cut, but my scanner
isn't large enough for this. You could pick up a copy of the catalogue
from OIBS at Mapusa (behind the Old Mapusa Clinic). Other places with
good collections of Goa books include Broadways (Panjim), Mandovi
Hotel Bookshop (Panjim) and Golden Heart Emporium (Margao). FN
--
FN * Independent Journalist http://fn.goa-india.org
M: +91-9822122436 P: +91-832-2409490