Yep, I agree with Simon about 'Slowjamz'; it's that heliumed-up vocal in the chorus that does it, innit?
Also rather partial to the new Sugababes. In fact, I pretty much like everything they do. Two caveats about their eminently hummable latest:
1) The video --- it's kinda sleazy. The girls trying way way too hard. Didn't the appeal of the Sugababes used to be that they were kind of ordinary-looking? This transmutation into pole-dancing temptresses doesn't do anything for me.
2) The lyrics --- it's like they are written by an AI attempting to simulate a zeroes' Pop song. All the individual words make sense, but the lines, the song as a whole, it makes no sense at all.