How to expose non Drupal tables in Views? I wonder what is the best way to allow the Views module to access external tables not in Drupal?

I tried the Data module, but it doesn't allow for a datetime datatype.
The data module is a good start.

You can skip the data module and create your own views type with hook_views_data()
Angie has an example here. 

Date times can be tricky, if you post another question with your specific problem with date times there may be a solution.

You don't specify if the DB is the same. You would need to define a second database in your settings.php if you need to connect to a different DB.