Perhaps this isn't a bug but it certainly is screwy.

I found that if I offered an alliance with a race that I had close relations to, I could then ask for any and all technologies they possessed as part of the deal. In this way, I was able to get over 2 dozen moderate-level technologies without offering any of my own (I was a tech-retarded civilization).

Just to be sure, I waited until I had close relations with yet another race and pulled the same move yet again. Granted, I had advanced diplomacy skills but their reaction seemed over-the-top.