Tubegroover,
I thought I'd put in "Feelings" by Maurice Albert but when I finally came down to your post I knew you won!
Some fantastic songs listed above and sorry to say many are not one hit wonders by any chance. Thelma Houston's song "Don't leave me this way" is featured on an LP which I happen to have, unfortunately her best "I've got the music in me, is missing in my collection but a dear friend of mine has it and what fantastic sounding record.
I want to add one song not mentioned in the list and am pretty sure it was a one hit wonder by Mureen McGovern and the tile of the song "The morning after" The song was featured in the movie "Posiden Adventure" probably dating back to 1975.
Another song which comes to mind is by Mary Hopkins title of which was "Those were the days" I know she had an LP out on Apple Records but none made it to the TOTP's in those days (1968). I hope this one qualifies as a one hit wonder, unless someone proves me wrong.
Surely I must say this thread is the most interesting one for me as well since so many memories are attached to many of the songs listed in this thread.
I wonder how "Rock On" would sound on a REL Subwoofer. I remember listening to it back then and always was impressed with its bass line.