How do I configure Ubuntu for a public computer?

How would you set up Ubuntu on a computer that will be used as public computer in a library?

I need the following features and user restrictions:

• On boot, a guest user should automatically be logged in.
• Only Firefox, Chrome and OpenOffice should be available for the guest user.
• The guest user should be able to write files to his/her USB stick, but never to the computer's hard drive.

Any guidelines on how to set up something like this? Is there perhaps a remix of Ubuntu created for this exact purpose?

You might want to have a look at these two programs: pessulus and sabayon

Especially sabayon is interesting, though it is a bit confusing! It can recreate a predefined session for a user at every startup, this session can then be totally restricted with pessulus. Then you just need to setup auto-login (Through the menu System>Administration>Login Screen) and you're ready to go.

1. Setting up the Guest account is pretty straight forward: System > Administration > Users and Groups Then follow this: Ubuntu StackExchange: How can user avoid entering password on bootup?
2. After uninstalling all the software using Applications > Ubuntu Software Center get Google Chrome from here: Google Chrome for Linux and install it.
3. This is really the tricky part. By default they're only allowed to download to the "Guest" home folder. You could change the home folders permissions or ownership to something else (baring in mind that the settings folder should remain owned by Guest. An alternative would be to have a script which re-created the Guest home folder on each login. For the USB drive reading that shouldn't be a problem as it's allowed by default.