avatar

If you want to assign not just a default avatar, but a random default avatar, that is possible with a setting in the Avatar Selection module.

(I almost made a module to allow a random avatar image to be pulled from a set uploaded by the administrator, in fact I was on my way to the Contributed Module Ideas group, but fortunately i kept searching and found this great module by Stella Power that has this random avatar feature as a bonus.)

You can set authoring information display per content type, which takes the user picture with it, but this should be more configurable.

May tie in as far as code needed with something i apparently want so much i've posted it twice:

Show authors of all revisions on an article of content

Node Authors module: give multiple people edit rights to specific content based on userreference field