If you have been using Ubuntu for a while, you probably know that after 30 boots Ubuntu runs a check on the hard disk. This “Fsck” check slows down booting a lot. AutoFsck runs the check on shutdown instead, and asks you if it is a good time first. If the occasional slow boot is a problem for you, AutoFsck is perfect.
The disk check runs has always been fairly quick on my two desktops, so it does not bother me. But running the check on shutdown makes a lot more sense. Most of the time there is no hurry to shutdown a PC. However, when a user starts up a computer, they usually want to use it as soon as they can. The developer of AutoFsck thinks that it should be included in Ubuntu 7.10, which I think is a great idea.