Remember though that it's supposed to still be a conversation, a give and take. I've been talked at for hours in the past without being able to get much of a word in, let alone ever tell them something about me. I just don't know how to politely tell someone to slow the fuck down/stop.
Sometimes people are lonely or just don't feel heard. When given the opportunity they relish being heard. It's nice you're a good listener, it can be therapeutic for the talker. I feel sometimes people work things out by hearing themselves say their thoughts out loud. There's nothing wrong with you interrupting them and reminding them how a conversation works.