Wanting to keep pages out of the SERPS that I felt shouldn't be there I started using the following robots.txt file on a SimpleMachines forum site of mine.
PLAIN TEXT
CODE:
User-Agent: *
Disallow: /index.php?action=search
Disallow: /index.php?action=calendar
Disallow: /index.php?action=login
Disallow: /index.php?action=register
Disallow: /index.php?action=profile
Disallow: /index.php?action=stats
Disallow: /index.php?action=activate
Disallow: /index.php?action=help
Disallow: /index.php?action=admin
Disallow: /index.php?action=pm
Disallow: /index.php?action=mlist
Disallow: /index.php?action=notify
Disallow: /index.php?action=post
Disallow: /index.php?action=markasread
Disallow: /index.php?action=sendtopic
Disallow: /index.php?action=printpage
Disallow: /attachments/
Disallow: /avatars/
Disallow: /Packages/
Disallow: /sitemaps/
Disallow: /Smileys/
Disallow: /Sources/
Disallow: /Themes/