I’ve only just noticed it – perhaps it’s existed for a while? – but I’m favouring the contextual tooltip execution in SoundCloud.com‘s app.
It appeals to my love of large clickable areas and a functional form. It’s almost possible to action most tasks (e.g. ‘Go to track’, ‘Save to favourites’, ‘Download’ etc.) by using a scroll wheel movement or vertical trackpad gesture by itself, leaving my cursor hand free to scratch things with – great stuff!