Just to repeat what's already the most common sentiment on this thread: Thanks Nick Naylor!
I realize that hold is better than rejection, but it still stings. Any advice on how to influence them to interview me? I've been doing some new volunteer work and I'm thinking about sending them an update, but I'm not sure I'll have another letter of recommendation in a timely fashion.
I would definitely send an update, HOWEVER I wouldn't do it just yet. That's a little too soon for me (but, since this is your application, you should go with your gut), but this suggestion really isn't based on any sort of secret knowledge. As with all things in this process, do what you think is best.
On another note, to allay the potential fears/stresses of hosting I thought I'd share with you how the hosting process works. When you receive an interview invite, there should be a link to the hosting request form which you'll need to fill out. If it's not in the initial e-mail, it might be in the confirmation e-mail once you choose your interview date (if such a confirmation e-mail is actually sent; I honestly don't remember). The link may also appear somewhere on the status page once you've been invited. You should complete the hosting form at LEAST a week before your interview. Requests for hosts are sent to the classes the week before your requested date; if you send a request for a host with less notice than that, we may not be able to set you up with someone.
At that point you should receive, within a few days, confirmation that you've requested a host from one of our hosting coordinators (which includes yours truly). If you're ahead of the game and won't be interviewing for a while, you won't be hearing from us for a while. As I said, we won't send out a request to host you until the week before your interview. It may be a day or two before you get confirmation that a student has agreed to host you - don't panic! This is why it's recommended that you have alternate plans made just in case (staying at the International House on campus is a highly recommended and cheap option, and the deposit/charge is refundable up to 24 hours before your arrival). Information on the International House can be found here:
http://ihouse.uchicago.edu/ (click "request guest accommodations" under quick links on the right side of the page). We'll try and give you ~24 hours notice if we can't get a host lined up for you. The notice is short because we'll try our absolute hardest to find someone for you, which may require guilt tripping someone the day or two before.
We only ask students to host you for one night, EVEN IF you put on your form that you'd like more than one night. If you'll need another night, feel free to ask your host (once you receive one) whether or not you can stay with them. In my experience my hosts were perfectly fine with an additional night, but we obviously can't guarantee this, and you'd need to set up those plans yourself. Again, the International House is a great option if your host can't host you and you need to stay another night.
Just a general note: please don't e-mail the admissions office about student hosts! They'll more than likely just forward your e-mail to one of us. If we don't e-mail you right away (i.e., within a couple of days), please be patient! It may be the last couple of days before a test or something like that. If you're concerned that your request didn't go through and you haven't received a confirmation after a few days, you're welcome to message me with your name and I'll check to see if we've received your request.
If you have any last minute issues, can't find a host, etc. and haven't been contacted by a hosting coordinator, please feel free to message me.
Let me know if you have any questions!
It sure comes fast...
My fantasy team is what gives me anger this year 
