The magazine describes one-hit wonders as acts whose second hit did not reach the top 25; they only included acts from 2000 to 2007, since someone from last year might just be taking a break.
No. 2 on their list is the Terror Squad for "Lean Back"; No. 3 is Crazy Town with "Butterfly"; No. 4 is MIMS with "This Is Why I'm Hot"; and No. 5 is D4L -- remember them? -- with "Laffy Taffy."