As of BeOS 5.01, you can grow or shrink a selection in the Tracker by holding down Alt while clicking. In other words, you can select a range of files without dragging, much as you would use the Shift key to select a range of files in Windows Explorer — select a file, hold down Alt, and select another file… all the files in between will be selected.
Stuart Adam (drake@madasafish.com) notes that you can still use Shift to select additional individual files that aren’t within the currenet selection range.
Note: This feature comes to you thanks to the OpenTracker project; 5.01 is the first BeOS release to include code changes from the open source community.