No, this isn't a post about McDonalds. This is a post about Merb (and DataMapper).
As the story goes, I was working on a project involving creating a new web application to match the features of a legacy java application, while maintaining the use of the same exact database. ActiveRecord was worthless in this endeavor. Even with excessive work I could not break it from its conventions.
Since Rails is utterly dependent upon AR I was forced to find an alternative. My saving grace was found with a reference to Merb (Mongrel+erb) by my cousin. Merb is agnostic in many ways. Most importantly with regard to the ORM (object-relational mapping) used. ActiveRecord is supported, as well as, DataMapper and Sequel. In making the switch, I also switched to using jQuery instead of prototype.
All in all, I'm loving it. The only downfall I have experienced is having to dump and restore my database whenever applying a change in my models to the database as the DM migrations are destructive.
Aside from this Merb (and DataMapper) are faster, lighter, and easier to contribute to (if I find a bug, or wish to add features).
As for the project that started this all: it is coming along far better than I could have hoped with Ruby on Rails.