On the server Endless Horizons we recently hosted a server-wide airship contest, to see who could build the most impressive airship. In the end it was close, with many large and , overall, fantastic entries. In the end, the winner was one of our donators, MistaStinky, and his airship as a reward was displayed above spawn (shown in the first picture), alongside some hot air balloons.
The second image shows where the airships were built and judged from, and the third and fourth images show more examples of entries which we had to decide a winner from.

If you would like to come and check out some of the airships, you simply have to log into our server:
Server IP: mc.endlesshorizons.co.uk
Website: www.endlesshorizons.co.uk

Note: Our server is still running on Bukkit 1.4.5, meaning that if you have upgraded to 1.4.6 you won't be able to join until we upgrade (hopefully very soon). But, here is a link to a thread on our website, explaining how to swap back a version..

Other links:
Endless Horizons PMC page: Link

Additional Notes

Survival Server!