Someone is answering my question and we keep going back and forth in the comments. It would be great if I could request a chat room for us to make it a more efficient discussion in a single click right from that screen (instead of 1. going to chat, 2. creating a room, 3. going back and inviting that person, etc . .)
You only need 100 reputation to create a chat room; make one and post the link to it in the comments so the answerer can join.
Odds are they have the 20 rep necessary to talk, but if not you can add them to the write access list so they're able to talk. They'll need 20 rep necessary to talk. You used to be able to prepend
chat. to any question URL to create a room (e.g. going to
http://chat.meta.stackoverflow.com/questions/79202/can-i-request-a-chat-with-someone-who-answered-my-question would make a room about this question), but the feature wasn't used very much, so it was removed when chat was rolled out to all sites
If you do chat about this, please consider taking the information learned in chat (or the link to the transcript) and summarizing it in the question, so that others can benefit from what you've learned.
I actually like the fact that the comments are posted and are public. We're not here to keep secrets; all information is public. In many cases, the comments add value to the answers either by clarifying them or showing how the final answer may have developed through constructive feedback from other experts.
Now, with that said, if the chat transcript could be automatically appended back to the original question either as a comment or on the side, that could be a cool way to add more value to the question.