All users of Contrib Toggle are recommended to disable the module from their sites until the critical issues discussed below can be resolved.
I have determined that significant architectural issues with how the previous releases functioned had the potential (if an error occurred) to render a user's site unusable though disabling critical modules, and requiring a restore from backup or manual re-activation of the modules in the database. This was unacceptable to me so I have unpublished the release. I recommend all users disable Contrib Toggle from their sites until an acceptable alternative is found. Changes in Drupal 7 mean that this issue would not occur there, so it is possible that the dynamic module activation features of Contrib Toggle may be able to be re-introduced there even if a satisfactory solution for Drupal 6 cannot be found.
Current issues
There are indications contrib_toggle might be incompatible with modules that have parentheses in their display names [e.g. GetID3()] or in their dependencies, [e.g. Filefield includes Filefield Meta which has a dependency on GetID3()]. Outcomes can include an unusable site if modules are disabled that should not be, when you save the modules page. If you have any modules installed that contain parentheses in their display names, you may wish to disable contrib_toggle until this is clarified.
When upgrading between Drupal core versions (e.g. 6.8 to 6.9) it is recommended that all non-core modules ("contrib modules") are deactivated first. When you have modules with multiple dependencies, this is a needlessly time-consuming and fiddly process. The Contrib Toggle module provides a button on the module configuration page (/admin/build/modules/) to mark all contrib modules for deactivation, reducing this process a simple two-click exercise. Click the "Disable Contrib" button, then click "Save Configuration" to actually disable the modules. Contrib Toggle automatically disables itself in this process.
Between core upgrades, Contrib Toggle also provides an mechanism for dynamic activation and deactivation of modules with dependencies. When Contrib Toggle is active, all modules on the module admin page can be activated and deactivated. Activating a module will prompt you whether you wish to activate any other modules it depends on. Deactivating a module will likewise prompt whether you wish to deactivate any modules that depend on it.