Command
up -n | grep available

Syntax
drush up -n | grep available

We can actually use the standard update command to list only the modules that have updates available using a couple of additional flags. We'll look at actually updating projects in the next video, but I wanted to show you this technique, as it can make finding available updates much easier.

The "-n" flag, automatically answers no to any questions that Drush may have. This means that we won't actually perform any updates.

The "| grep available" string takes the long list of updates, and filters them to only display lines that contain the word "available".

* I originally came across this tip on the GoodWheelMedia blog and I found it so useful that I wanted to go ahead and include it here.