Version:            (using KDE 4.3.4)
OS:                Linux
Installed from:    Archlinux Packages

Today, my sister was using Windows and I saw that Windows Media Player had an interesting feature: "song previews".

The way it works is very simple: when you hover a song in the media library, it shows a tooltip with a link that says "Listen preview" (or something like that). If you press that link, the player stops the current song and starts playing the one you wish to preview ("prelisten" would be more appropriated). When you put the mouse arrow away from the tooltip, the preview stops and the song you were listening continues playing.

I think the idea could be even improved, for example, when you want to preview a song, the player could start by the middle of it, or by a bookmark you had placed before (on WMP, it always plays song from the beggining).