Some free advice from an interviewer: I see a lot of the below-median folks are shooting for less selective firms, and that's a good first step, but you still need to remember your job as a candidate - give a firm a reason to hire you. It's not enough to say "I'll have a CLS degree and I'm normal so, here I am". Well, maybe that is enough at some places, particularly in a secondary market in which you have close ties. But generally, and especially in NYC, wont fly.
Maybe your pitch is "look at my amazing personality /charisma". That's a reason to hire you, not a lot of us lawyers have that.
But lets assume, for sake of argument, that you can't offer that, because you know, you're like the rest of us and a total dork. What then? Each candidate will have a different answer, but instead of chasing a unicorn like all of a sudden turning yourself into the most likeable guy/gal in the room, think about what you realistically can offer. Can you subtly imply you will work harder than everyone else? That you really want biglaw, that you're not just in it to pay off debt for 3 years and bail? (Youd be surprised how many people simply can't say that with a straight face.) Can you imply that you're very professional, have good experience in a high pressure environment and will be a useful resource from day 1? Maybe you have some specialized interest in a practice area that the first wants to hire for, but that isn't otherwise attractive to other candidates with better grades.
All the stuff you hear about turning an interview into a chatty, relaxed conversation is true. That will help a lot, and you have to make sure you don't come off as "pitch-y". But don't forget that everyone needs to give the interviewer a reason why you should be hired, and if grades aren't that reason, then you have to have something else and weave it into the narrative that you're following in your interviews.