From the DUH! Department, for an idea so simple you wonder why you didn't think of it:

A lot of people are bugged that Outlook 2003's Drafts folder doesn't have a preview pane. If you are one of them, create a custom Search folder that only searches Drafts. Don't use any criteria and all items will be shown in the Drafts Search Folder. Add it to your Favorites folder list for easy access.

You can enable Autropreview to show just the first 3 lines in the folder. Look on the View menu for this option.