fdisk -l will show you everything on your drives and a text editor will edit the file. But I guess you mean to fill in the details of the file by you giving it plain, er, language, and it writing it out correctly? There should be something. Slackware's install process could probably be adapted, since it writes out a starter /etc/fstab for you interactively. And I'm sure there must be gui things. It's not that hard to do with a regular editor, though.
Here's one if you've got KDE, I guess.
http://kfstab.sourceforge.net/
Search around.
program for edit fstab
