To convert a bzr repository to git (cwd: bzr repo):
$ git init &&
bzr fast-export pwd | git fast-import &&
rm -r .bzr &&
git reset HEAD

Bazaar Explorer is a desktop application for using the Bazaar Version Control System. It provides a high level interface to all commonly used features, launching "applets" from the QBzr plug-in to provide most of the functionality. Alternatively, the applets from the bzr-gtk plug-in can be used if it is installed. Bazaar Explorer runs on GNOME, KDE, Windows and Mac OS X. It requires Bazaar 1.14 or later and QBzr 0.11 or later.

Nice short (very high-level aka simple) introduction to bazaar (bzr) and alike.