Sign-up sheet type program?

[TheLordsServant]

I have a friend who helps coordinate a bus trip to Washington DC each year. She has asked me if there is a program that would allow people to sign up for a bus and a hotel room, and then people would be able to view how many seats were left on each bus, and how many spots in each hotel room. I've done a little research of my own, and haven't found much, but I thought maybe the [H] community might have some ideas that I hadn't thought of or heard of.

Also, I hope this isn't too vague of a question, I tried to explain it as best I could, but it's kind of hard to explain what she is trying to do.