What about techs that are unique to specific civilizations?  There were so many in GC2 you had to find where they were on the tree if you got one from trading.  It would be nice to have a find tech search option like there was for stars and planets.

Gets my vote - many times I curse in a similar way trying to find the detail of, or the main explanation for, a Tech/New Ability/blah blah,  in Civilization, and/or related weapons and technologies. I have increasingly found this the case with GalCiv. As the game expanded over the years its become quite a problem in Civilization - its getting that way now with GalCiv.

A simple key word search ability would meet the need nicely, with the output highlighting the related techs, and/or a colour scheme highlighting the affected/related tech squares.