Some of my favourite songs are one hit wonders especially this one:

http://www.youtube.com/watch?v=2JAXKIKehbc

Not quite a one hit wonder but close, another favourite:

http://www.youtube.com/watch?v=BUmK7IprcNo

I saw Simon Dupree at the Assembly Rooms in York in 1968.   Ironically, when I was visiting York a couple of years ago we had dinner there and it is featured in the ITV 3 advertising for the Yorkshire Tourist Board.

Lieutenant Pigeon formed one of the teams on 'Eggheads' the other day.

Here's a couple of those 'ashamed to admit I like' one-hit wonders that frequently feature on 'guilty pleasures':

http://www.youtube.com/watch?v=x_tW3vU3RyQ

(I'm not sure if she's miming really badly or if the video's out of synch)

http://www.youtube.com/watch?v=cIFeq4x_2Xc
(cheesy to the nth degree but tuneful)

That's quite ahead of its time - the middle section sounds like modern chill-out music.

I used to think 'Simon Dupree' was some mysterious band leader, but then I found out it was just a made-up name for the group that went on to become Gentle Giant...