Similar or related tools

bumpversion is the original project off of which bump2version was forked. We'll be merging back with them at some point (issue #86).
ADVbumpversion is another fork. It offers some features which are still work in progress here; it's definitely our desire to merge back (issue #121).
zest.releaser manages your Python package releases and keeps the version number in one location.
setuptools-scm relies on version control tags and the state of your working copy to determine the version number.
incremental integrates into setuptools and maintains the version number in _version.py.
Invocations packaging.release are a set of tasks for invoke. These assume your version is in _version.py and you're using semantic versioning.
python-semantic.release automatically bumps your (semantic) version number based on the types of commits (breaking/new/bugfix) in your source control.

Change log building

towncrier assembles a changelog file from multiple snippets found in individual (merge) commits.
releases helps build a Sphinx ReStructuredText changelog.
gitchangelog searches the git commit history to make a configurable changelog file.