To test DVC backends quickly here I enumerate some
interesting(completely my subjective view - Masatake) archives or repositories:
Add archives(or repository) you are interested in.

* tla/baz

** dvc itself

   $ bzr get http://bzr.xsteve.at/dvc/

* bzr

** bless binary editor

   $ bzr branch http://download.gna.org/bless/bless.dev

* cg

** linux kernel

   $ cg-clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git

* hg

** Xen and linux related codes

  $ hg clone http://xenbits.xensource.com/linux-2.6-xen.hg
  $ hg clone http://xenbits.xensource.com/xen-3.0-testing.hg

* darcs

** Ion-3 window manager

  $ darcs get --partial http://modeemi.fi/~tuomov/repos/ion-3