I would like to know if is there any way I can read the whole list of packages atmosphere handles or any sort of list of available packages?
If you mean you want to see what packages your app is using run this in your apps directory
meteor list --using
If you mean you want to access the raw data on atmosphere you can do this using DDP.
The data is stored in the packages
collection & you can access it by subscribing to packageMetadata
If you use meteor you can do (Server side)
var atmosphere = DDP.connect("https://atmosphere.meteor.com");
atmosphere.subscribe("packageMetadata");
var Packages = new Meteor.Collection("packages", {connection: atmosphere});
Once the subscription is complete you can view the packages in the Packages
collection.
This isn't limited to using meteor there are DDP modules available in other languages such as .NET, Nodejs & ruby to name a few