When I create a new Drupal site I usually end up with at least one custom module and several community contributed modules. To get the site working as it should, many configuration values need to be set on the various modules. This makes deployment onto a fresh Drupal instance painstaking and error-prone.
I would like to give my custom module the ability to configure all the other modules. Either on install or on the click of a button on my custom module's administration page, all the necessary configuration values on the other modules would be programmatically set.
How would I best go about doing this?
AFAIK, there's no way to achieve what you mean easily. I tend to put as much as I can in hook_update_N() implementations and do frequent DB synchronisations as described in my answer to this question. However that does not work when you already have a live server with which you will have to merge data.
To that purpose, I use various tools according to the need. No one is perfect, but here's however a small collection of my favorite ones:
Features. This is a new concept and a new module. The idea is pretty awesome: it allows you to define a set of configuration/modules/settings and to export them as a feature. This feature will then be installed as if it were a module on the target site. This module does not export every possible setting, but it does however do a good job with the modules that need the hardest configuration, as CCK, Views, ImageCache and others... You can see a screencast demo (~10 mins) here.
Backup and migrate. This is a more radical approach: it simply dump and rebuild the entire database on a target system. It is good only if you need to overwrite the target system completely.
Node export. This allows to export (and import) nodes from a drupal installation to another one. It supports bulk operations but - unluckily - it does not support the migration of attached files and images.
Deploy. Because of the limitations of node export I once looked into using this module (still in development). I finally did not, and preferred to do a merge of the production and staging databases, but the concept seems very valid, as it allows to import/export complex data type via SOAP.
Taxonomy import/export. I suppose the name is self-explanatory. It uses files to achieve the tasks (XML or CSV).
Installation profiles (suggested by ctford) are useful when configuring new sites. They allow you to specify modules to enable, theme to default to etc on installation. They can be quite convenient because there is a command-line tool called Drush that automates the building of installation profiles. The downside is that the profiles are designed to be used on installation - not deployment of an individual module. It might be possible however to take the configuration code generated by Drush and call it when your module is enabled.
Finally, you can find a collection of tools for importing/exporting data here.
HTH!