DEB packages are very easy to make, and they are used in cydia to make installable packages. However, usually people do not check DEB packages before they install them. If a DEB file overwrites any /System/ files that are important to the functionality of the iPod/iPhone, your device will have to be restored. If you wish to check which files are written (or overwritten). Use 7-Zip. You may download it here: http://sourceforge.net/projects/sevenzip/files/7-Zip/9.04 beta/7z904.exe/download If you find any destructive material in a deb file, I recommend that you tell one of the admins to remove the link.