While working on exercises for the 2011 release of our fundamentals book, I ran across a neat little behavior...not sure if it was in 2010, but it's cool just the same.
Run an oval duct main out at an elevation, 16x12 is size, at about 12'. Leave the end hanging out in space. Run the air terminal command, and place the air terminal over the main - without selecting, watch for a duct centerline to be highlighted and an extension snap to appear (make sure you have this snap on). With the new properties dialog on, set the elevation for the air terminal at 8', and then place the terminal directly under the duct using the extension snap.
The branch to the air terminal will automatically connect into the main, complete with tap or take-off as specified by the main duct type. Try it out - it's really a time saver...and we'll have pictures of it in the book. This one may even make it to video...!!!!
Later - David B.