debshare.create is a hackish script used for producing .debshare files, which are basically "self-executable", monolithic archives containing several .deb packages. A .debshare file is meant to install one (or more) applications that it contains, complete with all its dependencies. This facilitates easy sharing of applications across computers using a single file, as opposed to multiple .deb packages. This idea was originally meant for Ubuntu systems, but there should be no reason why it shouldn't work on other similar distributions. Technically, a .debshare file is a bash shell script with a binary payload (a tar archive with the .deb-s) appended to it.
