I have created a page with my tips and exercises for long-haul flights or ie long train- or coachrides. It is filed under Pages in the right column, or use this link.
I will soon make use of them myself again, as I have a 9-10 hour busride from Edinburgh to London coming up. Hopefully there will be more than one stop along the way so I can get up and exercise the leg.
Update: Download a PDF-file with my inflight exercises here.