Using AngularJs and MongoDB/Mongoose
You'll need an interim step there. Going directly from Angular to Mongo will not work out. If you want a generic REST interface to Mongo with which you can utilize Angular's bundled $http services, take a look at the list of REST services on Mongo's site.
Mongo REST Services
http://www.mongodb.org/display/DOCS/Http+Interface#HttpInterface-RESTInterfaces
Angular $http Service:
http://docs.angularjs.org/api/ng.$http
There's a lot of different options here, but this is likely the easiest way to get up and going.
The interim step has been provided by a npm module, angoose. It does exactly what you asked for: making the mongoose models available as Angular injectable factories. All you need to do is just including a script tag in your html file.
angoose module:
https://npmjs.org/package/angoose
Disclaimer: I'm the contributor of angoose module.