On the WSPRnet website DM1RG posted some results obtained using a 30m dipole 1.3m long, the "Kurz Geratener Dipol". His 5W signal made it all the way from Germany to Australia. He finds the KGD to receive only 3 to 5dB worse than his "big vertical antenna."
I tried translating the article about the KGD using Google but it didn't make enough sense for me to understand how to make one. Perhaps someone will figure it out and publish a better explanation. It looks to me to be an interesting idea for anyone with antenna restrictions or simply wanting a second antenna so they can run WSPR or monitor a band while they operate somewhere else.