Josh Eaton

Allows users to report inappropriate content across a site’s content types. An email is sent to the admin user and the report is logged in the WP Admin under Dashboard > Content Reports.
Administrators can choose which post types to enable the report link and whether the link should appear before or after the content.

Community Watch

Allows users to report inappropriate content across a site's content types.

spot-the-cat

The contest module allows your site to host random games of chance, “Sweepstakes”. Where users can enter to win prizes via a random drawing.
Upon installation a custom content type, (contest) and user profile fields are created.
While a user must complete their profile to enter the contest. To create a low bar for anonymous users to enter. They can fill-in their personal information into the entry form and they will be enter into the contest and a user will be created for them. Logged in users with complete profiles can just click the “Enter Contest” button.
Winners can be selected via a contest’s admin page or the entries exported and printed for a public drawing. Publishing winner’s is a seperate step to allow for confirmation that the rules have been followed.
The same export, (a CSV compatible with Excel) can be provided to sponsors or affiliates for marketing purposes.
I’ve run on several sites and it works pretty well at getting the community and sponsors involved. Sponsors put up prizes which encouraged users to join the site. This expanded our email list which was returned to a contest’s sponsors for marketing purposes.

Contest

Allows users to enter to win prizes via a random drawing, (sweepstakes).

Community Watch vs Contest