Sometimes I am testing beta versions (for example when I suggest a feature and the author of the software sends me a beta version to test).
For many applications a beta version is available for download at the homepage.
One example is Firefox, there are Nightly versions and Aurora versions available to the public, so everybody can try them.

I know many other users (friends) that have beta versions installed.

So you should detect that a installed version is a beta version and also label this in the list of applications (by adding "(Beta)" or "(Nightly)" behind the name).

Next you should add an easy way for users to report that an detected application is a beta version (see suggestion "Report Errors").

If the user has a beta version installed and there is a new beta version available, then you should report this, but only to users that have a beta version.

In the Configuration you should add a checkbox "Report Beta versions" at the new section Scan options (this section is needed for other suggestions).
This checkbox is not checked by default.

If beta-versions is checked, then available beta versions are reported in the column "Available Version".
Also here the text "(Beta)" should be shown.