You probably know about dependencies in modules and how to declare them in a module's .info file. In case you're not familiar with the concept, it looks like this:
dependencies[] = imagefield
dependencies[] = nodereference
dependencies[] = content_copy
dependencies[] = views
dependencies[] = imagecache
(Slightly different in Drupal 5.x - be warned!)
Each one of those modules must be enabled before Drupal will allow you to enable the module you want to install. Neat, huh? But there is a problem: