(Most of this information is from Stanislav Linke's website)
There is a bug in Terror From the Deep's research tree. What happens is that when you research some things 'out of order' (according to the game authors' preference, apparently) you are no longer able to initiate the research of some alien artifacts. As far as I know, the only way to avoid this error is to research in the 'correct' order, specifically: Research the MC Lab after you have researched the MC Reader, research Zrbite only after you have have researched the Disruptor Pulse Launcher, the Live Deep One after Magnetic Navigation, Tasoth Commander after Leviathan, and another involving alien sub contruction, but there are other undocumented ones. If you have already encountered this bug, there is help for you. Stanislav Linke has created a website that will let you customize a research tree for your game to work around the problem. This solution can be found here:
It should in fact be the other way around, as per this article on UFOPaedia (and other research trees). It's confusing people so I think it would be a good idea to fix it.
The second thing should be posted in this thread. The list needs updating, TFTD (CE version) is now offered through Steam and UFO Defense can be played if you have a subscription to GameTap (gold, I think). It may be a good idea to check if the other sites mentioned in the thread still sell the games.
On a side note, I was wondering about the site news, it rarely gets updated. There isn't lots of news these days, but every once in a while there is something that is worth posting. Is it the fault of everyone's despised enemy Time? And can anything be done about it?
That's all from me today.