you also have the Krogan that is trying to win a girl over with poems.

I felt so bad for that Turian being in the "friend zone" with that quarian.  :(  
 
"Maybe later we can go catch a vid"  :(

Take Jack into the restroom in Dark Star, she'll  talk about how she was raped and ended up killing everyone after it.
 
Taking Legion to do pretty much anything with Tali is also comedy gold
 
Mordin singing is fucking amazing if you haven't heard it

The Crime Lord, Fist, from the first game can be located in the lower level of Afterlife after a certain point in the story. He's not a crime lord anymore, and he asks you to leave him to the only thing he has left - whores. 
 
Around the cabs on Ilium, near where you can buy the fish, there are multiple Asari family units standing around talking. It's kind of interesting, because one of the young Asari has a Salarian for a Father and he's trying to buy her a present which she will remember him by. Salarians only live around 40 years while Asari live to 1000, so It's kind of sad. There is also one family of a mother and daughter talking about how the father was a Batarian and she got a lot of his personal traits. 
 
If you talk to the salesman in the Weapon store on the top floor of the Citadel, there'll be an option to ask him about something where he will start acting out a scene where he is hunting some sort of animal. It's funny to note because he is given the animations of a character in combat, he even takes cover behind the counter. When he does, Shepard leans over and tries to look down behind the counter... it's hilarious. I've never seen a more lively Turian! 

I murdered Fist so i'm betting he ain't around!

If you bring Legion on Tali's loyalty mission you get some pretty good dialogue

I totally missed the conversation Brad talked about on the podcast, you know where two Krogan talk about boning an Assari, does anyone know where/how to trigger it?
 
Also the bachelor party in Eternity is pure gold. "So you humans celebrate eternal matrimony by risking infidelity?" and the conversation about which species resembles the Assari stripper more.
 
Eternity is awesome any way with the matriarch bartender and indeed the friendzone trapped Turian. I also felt the "Humans always just want me to take my mask off" is  a sting at the entire Mass Effect fanbase.

"I totally missed the conversation Brad talked about on the podcast, you know where two Krogan talk about boning an Assari, does anyone know where/how to trigger it?  Also the bachelor party in Eternity is pure gold. "So you humans celebrate eternal matrimony by risking infidelity?" and the conversation about which species resembles the Assari stripper more.  Eternity is awesome any way with the matriarch bartender and indeed the friendzone trapped Turian. I also felt the "Humans always just want me to take my mask off" is  a sting at the entire Mass Effect fanbase. "

Anything Zaeed does is comic gold. I love that guy. His background animations during the finale were hilarious.

When you start Legion's personal quest, there's a cutscene where Joker does an impersonation of him... gold, Jerry, gold.

Lots of people don't talk to EDI after a certain point. Doing so is very informative.

Man, I wish I got Legion.  By the time I found out where I could get him, I missed the opportunity.  Gives me even more reason to play my renegade playthrough afterwards.

@Nictel:
They only talked about Asari for a moment when I first talked to them.  Basically saying they are too soft and there isn't anything to grab on to.  I don't think they'll mention it after you finish talking to them after the quest.  :/ 

" Man, I wish I got Legion.  By the time I found out where I could get him, I missed the opportunity.  Gives me even more reason to play my renegade playthrough afterwards. "

So many great moments, from Eternity:
 
Are the Asari really manipulating all the other species minds so they find them attractive?
 
Fleet and Flotilla
 
At some point if you stay around the Turian and Quarian the Quarian gets mad and ask you to leave so they can have privacy.
 
I also never got the convo about the Asari boning!
 
 If you go into the crew quarters on level 3 after every main quest earlier in the game you'll get to overhear a storyline about one of the crew members who has family on a planet that may be subject to a collector attack.
 
In Afterlife, order a drink from the Batarian bartender on the lower level and you'll be poisioned, go back to confront him and have multiple option has what to do.

Does anyone know how to update the conversation with characters? My legion conversation just ends up with him saying "We are trying to form a  consensus`". Do I have to do stuff?

It was actually kinda cool to hear Nihilus brought back up in this game.  Apparently he and Samara had an epic battle that he escaped by putting a civilian in a near-death predicament.

I totally missed that I could have killed Samara and recruited Morinth into my party to replace her. Then I could have let her seduce me on board my ship and gotten a sweet game over screen for it. I was going Renegade too on that playthrough.. damn.

"If you bring Legion on Tali's loyalty mission you get some pretty good dialogue "

" @megalowho: I'm pretty sure you have to be renegade to turn on Samara, I was never given the option. What did you have to warn Morinth once you got into the apartment? "

On illium, if you let the Rachni queen live, you receive a message from her via an asari near the beginning.
 
This is by far the best though.
 

" @Surely_Youre_Joking said:

" @megalowho: I'm pretty sure you have to be renegade to turn on Samara, I was never given the option. What did you have to warn Morinth once you got into the apartment? "

It just says "Kill Morinth" or "Kill Samara." If you choose "Kill Samara" I think you need to pass a 100% renegade check. "

" the monkey in the back of the krogan scientists place... it flashed up "punch"  I did "

" Oh I got a really good one I totally forgot about!   On Illium the nightclub/bar Eternity.  Talk to the bartender... at some point you can ask for a drink and she'll set you up on the machine next to her.  Take note of what she looks like.  Open the drinking vender and buy the Vorcha mystery booze... it is the most expensive one at 25 credits.  After drinking it talk to the bartender again.  She should now have makeup on and a slightly younger complexion.  SHE GETS MORE ATTRACTIVE ONCE YOU ARE DRUNK! :D  I thought maybe drinking more would make her more attractive but it doesn't seem to. "

" On illium, if you let the Rachni queen live, you receive a message from her via an asari near the beginning.
 
This is by far the best though.
 

"

The Ad for the movie about the first Haner Specter was pretty funny.