(According to Discogs anyway) A girl group called The Boys (don't ask) released one single, a great cover of Jackie Deshannon's "Splendor In The Grass": Even more curious/amazing, they actually got on TV! Their manager must've had some really good connections: Fan tribute page w/ some rare photos: The Boys - girl group 1965 Any other memorable one-shots out there?
I didn't feel like going into detail on things like that. (I think The Boys actually released three sides -- rereleases w/a different flip) I hope people will show some common sense. Please be gentle.
HSAS (Hagar, Schon, Aaronson, Shrieve): Through the Fire was their only album. Of course, the members themselves played on many other albums beforehand.
The Bees - Voices Green And Purple. There must be a ton of 60s garage bands who only had one single released.
The Shaggs later released a second album, Shaggs Own Thing. It's not nearly as memorable being largely uninspired covers. Also they'd taken music lessons and learned to play their instruments (sort of).
One of my favorite records of all time, Guitar Romantic by the Exploding Hearts. Sadly, three quarters of the band was killed in a car accident just months after it was released. A huge loss that still stings, even 15 years later.
Hampton Grease Band. Music To Eat. 2LP Set. Claimed to be the second worst selling album in Columbia's history. They went on to make a deal with Zappa's Bizarre/Straight label. That fell apart and the band split up. Too bad, as Music To Eat is a fantastic album.