Utility Models/Classes

I've created some utility classes that pull data from multiple models. Right now the class declarations are just tacked onto the bottom of the primary model, but I want to move them somewhere else -- in a seperate .rb class.

I'd prefer not in lib, so I don't have to restart rails for debugging/ development.

I tried putting them in standalone files within the models directory but the other models can't seem to find them (const missing)

Must they be ActiveRecord children? I'd prefer not to have the baggage.

I must be missing something simple here...