There is a class of achievements in Diablo 3 that requires you talk to the townsfolk such as this one.
Does it require you to sit there and wait for the dialogue to finish or can you skip them and still get the achievements?
Contrary to the current accepted answer, it appears that you do not need to listen to dialogue for a minimum of 8 seconds. I tested this today and made a quick video of my results, see it here.
In summary, you can quickly skip through all of the dialogue and still get credit toward the achievements.
Edit: I have run more tests, here is a link to a Youtube video where I skip through 18 conversations of varying lengths at full speed and get credit for all of them. It's not exactly a riveting video, but I think that it sufficiently supports my answer. Here is the video (the footage is sped up to make the video shorter).
You can skip the conversations (by pressing the X to the dialogue boxes, pressing the space key or the escape key) and still get the achievements, ONLY after you've listened to the dialogue for at least 8 seconds
This is now proven through playing through the game and regularly checking for the achievement updates.
You have to listen to the whole conversation to get the Achievement for conversations, atleast that is how I did it. However it doesn't matter how quickly you listen to the whole conversation, so you can spam space through it all and still get it. I know this for a fact since I went through and quest jumped to get some conversation options I had missed.