You can just type bma[TAB][TAB] and it will list them all.

If you know the type of resource you are working with, you can use TAB completion to see it's commands:

  $ stack-
  stack-arn            stack-exports        stack-tag-apply
  stack-asg-instances  stack-failure        stack-tag-delete
  stack-asgs           stack-instances      stack-tags
  stack-cancel-update  stack-outputs        stack-tags-text
  stack-create         stack-parameters     stack-tail
  stack-delete         stack-recreate       stack-template
  stack-diff           stack-resources      stack-update
  stack-elbs           stack-status         stack-validate
  stack-events         stack-tag