I sincerely hope you managed to grab Fallout, Fallout 2, and Fallout Tactics while they were being offered for free on GOG.com. The games are no longer purchasable, as was made clear during the giveaway, however if you do own them on the service you'll continue to have access to them and their bonus content going forward.
"These classic titles have been with us since day one, that is for over 5 years now, and they were always one of the highlights of the selection of games that we offer," wrote GOG.com. "There are very few titles in the history of computer role-playing games, that have had so much impact on the gaming landscape, players' expectations, and even the popular culture."
This removal is believed to be a result of Bethesda Softworks purchasing the rights to the franchise from Interplay. Curiously, these specific titles are still for sale on Steam. Sad to see this happen, as Fallout was one of the major attention-grabbing properties back when GOG.com was first starting out and its inclusion in the library helped legitimize the site.