Commonwealth War Graves Commission

This is  a wonderful resource for anyone who has ancestors who died in either of the World Wars. The database is fully searchable and contains 1.7 million soldiers. There are photographs of the cemeteries and of the grave stones.
In addition, the website contains historical information about various wars, a list of casualties for each country, information sheets for various battles and so much more. The website is free and the CWGC is non-profit. Take a look and see what you can find about your military ancestor:

http://www.cwgc.org/

There is also a photographic project for the Commission:

"The Photographic Project (TWGPP) was started by a dedicated group of volunteers a few years ago. Recently, following discussion with the Commonwealth War Graves Commission, (CWGC) the project has become a joint venture. Family Historians can now obtain a copy of the photograph of a grave or memorial which for many is impossible to visit due to its location. The intention of the TWGPP is not only to include images of official CWGC gravestones but also photographs of family graves which commemorate an individual. A surprising number of these have already been included. If you are able to provide a digital image of your family gravestone then details of contact addresses and advice on how to do so is available on the TWGPP website. This project has proved very popular and many individuals have been able to include graves from earlier conflicts that predate 1914. Should you have images from anywhere in the world where  military personnel were based then these should be submitted."

~by Barbara Parry, BRANTches August 2011