If you happen to be a big-time "movie scholar", one of the biggest joys of your love for cinema would have to be when you locate a long lost, famous movie for all the world to see.
I'm sure that 1978's discovery of 1928's The Passion of Joan of Arc ranks highest when it comes to finding a treasure (Feel free to prove me wrong) but are there more (Popular and respected) movies that became lost but were eventually found?

Another one I can think of:
The Ghoul with Boris Karloff. Notable for being Britain's first horror talkie. I still can't find any info on what year it was found (It surpassed the mid-70's because one of my monster-movie books, "Classics of the Horror Film", still had the movie lost by that time)

Any more?

Murnau's Phantom and Tod Browning's The Unknown were considered at one point to be "lost" films. The film itself is obviously not lost, but the recently discovered Metropolis footage was thought to be destroyed.

(Speaking of Murnau) As many of you probably know, Nosferatu was this close to becoming extinct when the Stoker estate destroyed many prints. Thankfully, the movie managed to survive the century and beyond.

http://en.wikipedia.org/wiki/List_of_rediscovered_films
1910's Frankenstein was one I remembered.
Not sure how accurate the wikipedia article is.

Thanks, regardless of accuracy.

Only fitting that an Ed Wood film would show up in a yard sale.

It's unfortunate Gena Rowlands has prevented the original cut of Shadows from every receiving a public release. Jonas Mekas considers it markedly superior to the second, less experimental version. I'd love a DVD edition with Carney commentary.

Spider Baby (1964 / 8) was considered lost for a while (probably because no one had gone looking for it).

I once paid to see a special screening of the Orson Welles film "The Magnificent Ambersons". Sadly I could not tell you a single thing about it aside from it being in B&W.

I gather that it was heavily edited and could not say the extent, if any, to which this print was restored.

(I'll get my coat).

I'll get the door.