By "One Album Wonders" , I thought you meant artists that only made one great album, so it threw me for a loop. There's a few notable acts i've liked that didn't make more than one full length LP.
The stuff that I remember anyway...
The United States of America - The United States of America 1968
Breakbeat Era - Breakbeat Era 1998
Dragonfly - Dragonfly 1968
Black Devil - Disco Club 1978
Pieter K - Everything All the Time 2002
Joe Meek & The Blue Men - I Hear a New World: An Outer Space Music Fantasy 1959
Di Melo - Di Melo 1975
Blind Faith - Blind Faith 1969
Doubting Thomas -The Infidel 1991 (the best cEvin Key collabo project hands down)
Jeff Buckley - Grace 1994
Akufen - My Way 2002
Lawgiverz - Data Treat 2008
Fever Ray - Fever Ray 2009
Thom Yorke - The Eraser 2007
(iffy on it since it's not as good as Radiohead, but it's still solid)
Lovage - Music to Make Love to Your Old Lady By 2006
Exile - Pro Agonist 2005
Fapardokly - Fapardokly 1967 (half of it is great and the other half is forgettable)
The Avalanches - Since I Left You 2000
Sneaker Pimps - Becoming X 1997 (they technically kept the band going under the same name, but without Kelli Dayton it sounded like a completely different project)
Somethng like The Crazy World of Arthur Brown
would've made it in there too if he didn't release follow ups decades later. List would've been much bigger if the title was "Two Album Wonders".