Is it possible to create a new repository in Bitbucket by using command line Git? I have tried the following:
git clone --bare https://username@bitbucket.org         
        Here is @hannesr's script tweaked a bit to accept input from prompts:
# startbitbucket - creates remote bitbucket repo and adds it as git remote to cwd
function startbitbucket {
    echo 'Username?'
    read username
    echo 'Password?'
    read -s password  # -s flag hides password text
    echo 'Repo name?'
    read reponame
    curl --user $username:$password \
         https://api.bitbucket.org/1.0/repositories/ \
         --data name=$reponame \
         --data is_private='true'
    git remote add origin git@bitbucket.org:$username/$reponame.git
    git push -u origin --all
    git push -u origin --tags
}
You should place this in your .bashrc or .bash_aliases.