MongoDB is the only officially supported database for Meteor until this month. Now, Meteor has Redis Support too. This is currently labeled as an experiment, but it works.
Velocity is the official testing framework for Meteor 1.0. Most importantly, this is a community powered project. Currently, velocity is under heavy development. But now you’ve documentation and resources to try velocity with your app.
Recently, Sacha made some quite impressive changes to Telescope and now it’s much cleaner, modular and works smoothly than before. Read about some of these recent changes.