BitbucketSync is a python command line utility that lets you synchronize all repositories that you own (default) on Bitbucket to a local directory on your machine. By using the --with-aliens switch, you can also synchronize repositories that other developers shared with you. The directory names of the ones that got shared end with two underscores and the developer's name (so forks with the same name don't screw things up).
Just grab a copy of sync.py. There are no dependencies beside the hg command, anything else is just the Python Standard Library.
Command Line Usage
Usage: sync.py [options]
-h, --help show this help message and exit -u USERNAME, --username=USERNAME Your username on bitbucket.org -p PASSWORD, --password=PASSWORD Your password on bitbucket.org -d DIRECTORY, --directory=DIRECTORY The local directory to sync to [Defaults to the current directory] -a, --with-aliens Also sync repositories that other people shared with you -v, --verbose Verbose output
To speed things up, all repositories are fetched in parallel. Make sure that you enabled SSH compression for bitbucket.org by following the steps on Enabling Compression.