See the Fools Garden - Lemon Tree parody
(written by me)

See the Eagle Eye Cherry - Save Tonight parody
(written by me)

See the Beatles - Help parody
(written by Owen Jollands)

See the The Mamas and the Papas - California Dreaming parody
(written by Matthew Kitson)

Health warning:

The pages linked to above, when viewed on Internet Explorer, contain midi background tunes.