I need to send one email for changes to multiple lists/document libraries. Is this at all possible??? And to make it even more complicated I need this one email to be sent weekly containing all these changes.
Yes, totally possible with workflow. Create a 3rd list with bunch of columns (for example, ListAName, ListBName) to capture information from various lists. Then when the record in the 3rd is complete (meaning all populated with required information from source lists or libraries) then you would calculate 7 days from the last modification date on the 3rd list and send an email. With nintex this could be piece of cake (given you are somewhat fluent designing workflow).