The Hurd presently has only support for CD-ROMs, but not for audio extraction ("grabbing"). As a result, cdparanoia (and other extraction libraries/utilities) are not available; and many other packages depending on these can't be built in Debian GNU/Hurd either.
Adding support for audio extraction shouldn't be too hard. It requires implementing a number of additional ioctl()s, generating the appropriate ATAPI commands.
The goal of this task is fully working cdparanoia in Debian GNU/Hurd. It will require digging a bit into Hurd internals and ATAPI commands, but should be quite doable without any previous knowledge about either.
Possible mentors: Samuel Thibault (youpi)
Exercise: Look at the implementation of the existing ioctl()s, and try to find something that could be easily added/improved. If you don't see anything obvious, talk to us about a different exercise task.