None of them succeeded in making those words stop being used as insults by people who hated them.

To the extent that this was ever the intention, quite true.

I forget the broader sociolinguistic term, but within the context of black history, this is known as "signifying". The black adoption of the word "nigger" (which I see no reason not to use in the context of our present discussion) as a term of approbation goes back a lot further than the 1960s. It was not a conscious effort to influence mainstream culture through language until much later (the '60s); I suspect, though I don't know, that this was the case with your other examples as well. Signifcation originally served (and arguably still serves) to build solidarity and morale.

I would say that, adapted for political ends, the phenomenon indeed had almost as little effect as later campaigns to "debunk stereotypes" and to promote various flavors of Newspeak.

I don't want to tread too far down this line, though. Political argument in the Chatterbox is one thing, but I'm afraid unvarnished opinions on such subjects are a dangerous thing here. Suffice it to say, I think we will profit not at all by renouncing the word "geek". Nobody will forget the word.

What we gain from the word "geek", is a sense of identity; and what other word suits? "Intellectual" and "hacker" both have rather specialized connotations; I identify with both, but many who presently call themselves geeks do not. And in any case, people today have chosen the word for themselves; geeks are a cultural reality, because they think they are. To deliberately eschew the word will not make anti-intellectuals stop using it as a pejorative... but it may isolate their victims.

Why not be bold, then? For my part, I'm a Scientific American-readin', code hackin', dyed-in-the-wool propellerhead. Geek is beautiful. Crank up the Devo, and bring out the polyhedral dice!